A metronome ticking the beat for performance especially with moving tempo, and having display looks like conductor's baton so that watcher can precisely predict beat timing to catch up the moving tempo. It has tapping button to record all the beat duration time data on memory. With the data on memory all the beats can be reproduced. Partial modification of beat duration time is also possible by tapping. Dedicated device uses vertically placed light emitting element array. Emitting point moves like ball thrown upward. Bound timing is beat timing. The metronome opens new way to produce music minus one or karaoke media.