Provided is a device for playing audio with improved convenience, wherein music can be played such that oneness with the actions of the user can be obtained at all times, without giving the user any unnaturalness whatsoever such as unpleasant sensations. After starting playing of music data through such as an audio signal output processing unit 31, action tempo of the user is detected by an exercise information analyzing circuit 23, based on detection output from an exercise information sensor 24, and in the event that the difference between the detected action tempo of the user and the tempo of the music data being played is not a predetermined range, music data with a tempo of which the difference as to the action tempo of the user is within the predetermined range is searched by searching means such as a music playing data generating device unit 22, and a control unit 10 changes the music data to be played so as to play this searched music data.