diff --git a/lib/fluent/plugin/in_tail.rb b/lib/fluent/plugin/in_tail.rb
index 88556ca6ab..2aa2122945 100644
--- a/lib/fluent/plugin/in_tail.rb
+++ b/lib/fluent/plugin/in_tail.rb
@@ -502,9 +502,13 @@ def update_watcher(tail_watcher, pe, new_inode)
       new_target_info = TargetInfo.new(path, new_inode)
 
       if @follow_inodes
-        # When follow_inodes is true, it's not cleaned up by refresh_watcher.
-        # So it should be unwatched here explicitly.
-        tail_watcher.unwatched = true
+        # If the old inode still exists, we can't unwatch it.
+        # If the old inode disappears, we should unwatch it here because
+        # `refresh_watcher` can't detect that the inode disappears.
+        # (It is because the path of `@tails` will be overwritten here.)
+        # (It is not a big problem if we don't unwatch here, as long as we make
+        # sure to detach it. The position will be cleared on restart eventually.)
+        tail_watcher.unwatched = true unless expand_paths.key?(tail_watcher.ino)
 
         new_position_entry = @pf[new_target_info]
         # If `refresh_watcher` find the new file before, this will not be zero.
diff --git a/test/plugin/test_in_tail.rb b/test/plugin/test_in_tail.rb
index 81bf0dfa7d..789ba12f3a 100644
--- a/test/plugin/test_in_tail.rb
+++ b/test/plugin/test_in_tail.rb
@@ -2704,22 +2704,14 @@ def test_updateTW_before_refreshTW_and_detach_before_refreshTW
 
       assert_equal(
         {
-          # TODO: This is BUG!! We need to fix it and replace this with the next.
-          record_values: ["file1 log1", "file1 log1", "file1 log2", "file1 log2", "file2 log1", "file2 log2"],
-          # record_values: ["file1 log1", "file1 log2", "file2 log1", "file2 log2"],
+          record_values: ["file1 log1", "file1 log2", "file2 log1", "file2 log2"],
           tail_watcher_paths: ["#{@tmp_dir}/tail.txt", "#{@tmp_dir}/tail.txt", "#{@tmp_dir}/tail.txt1"],
           tail_watcher_inodes: [inode_0, inode_1, inode_0],
           tail_watcher_io_handler_opened_statuses: [false, false, false],
-          # TODO: This is BUG!! We need to fix it and replace this with the next.
           position_entries: [
-            ["#{@tmp_dir}/tail.txt", "ffffffffffffffff", inode_0],
+            ["#{@tmp_dir}/tail.txt", "0000000000000016", inode_0],
             ["#{@tmp_dir}/tail.txt", "0000000000000016", inode_1],
-            ["#{@tmp_dir}/tail.txt1", "0000000000000016", inode_0],
           ],
-          # position_entries: [
-          #   ["#{@tmp_dir}/tail.txt", "ffffffffffffffff", inode_0],
-          #   ["#{@tmp_dir}/tail.txt", "0000000000000016", inode_1],
-          # ],
         },
         {
           record_values: record_values,
@@ -2802,7 +2794,7 @@ def test_updateTW_before_refreshTW_and_detach_after_refreshTW
           tail_watcher_inodes: [inode_0, inode_1, inode_0],
           tail_watcher_io_handler_opened_statuses: [false, false, false],
           position_entries: [
-            ["#{@tmp_dir}/tail.txt", "ffffffffffffffff", inode_0],
+            ["#{@tmp_dir}/tail.txt", "0000000000000016", inode_0],
             ["#{@tmp_dir}/tail.txt", "0000000000000016", inode_1],
           ],
         },
@@ -2861,9 +2853,10 @@ def test_updateTW_after_refreshTW
         #     This overwrites `@tails["tail.txt"]`
         d.instance.refresh_watchers
 
-        # `watch_timer` calls `TailWatcher::on_notify`, and then `update_watcher` updates the TailWatcher:
+        # `watch_timer` calls `TailWatcher::on_notify`, and then `update_watcher` trys to update the TailWatcher:
         #     TailWatcher(path: "tail.txt", inode: inode_0) => TailWatcher(path: "tail.txt", inode: inode_1)
-        # The old TailWathcer is detached here since `rotate_wait` is just `1s`.
+        # However, it is already added in `refresh_watcher`, so `update_watcher` doesn't create the new TailWatcher.
+        # `update_watcher` only detachs the old TailWathcer here since `rotate_wait` is just `1s`
         sleep 3
 
         # This adds a new TailWatcher: TailWatcher(path: "tail.txt1", inode: inode_0)
@@ -2886,22 +2879,14 @@ def test_updateTW_after_refreshTW
 
       assert_equal(
         {
-          # TODO: This is BUG!! We need to fix it and replace this with the next.
-          record_values: ["file1 log1", "file1 log1", "file1 log2", "file1 log2", "file2 log1", "file2 log2"],
-          # record_values: ["file1 log1", "file1 log2", "file2 log1", "file2 log2"],
+          record_values: ["file1 log1", "file1 log2", "file2 log1", "file2 log2"],
           tail_watcher_paths: ["#{@tmp_dir}/tail.txt", "#{@tmp_dir}/tail.txt", "#{@tmp_dir}/tail.txt1"],
           tail_watcher_inodes: [inode_0, inode_1, inode_0],
           tail_watcher_io_handler_opened_statuses: [false, false, false],
-          # TODO: This is BUG!! We need to fix it and replace this with the next.
           position_entries: [
-            ["#{@tmp_dir}/tail.txt", "ffffffffffffffff", inode_0],
+            ["#{@tmp_dir}/tail.txt", "0000000000000016", inode_0],
             ["#{@tmp_dir}/tail.txt", "0000000000000016", inode_1],
-            ["#{@tmp_dir}/tail.txt1", "0000000000000016", inode_0],
           ],
-          # position_entries: [
-          #   ["#{@tmp_dir}/tail.txt", "ffffffffffffffff", inode_0],
-          #   ["#{@tmp_dir}/tail.txt", "0000000000000016", inode_1],
-          # ],
         },
         {
           record_values: record_values,