To obtain a playing controller in which playing is instantly changed to desired playing.

A control signal generating means 30 generates control signals to converge errors in the amount of compression and expansion based on changed information to zero and to instantly change swing playing even though reproducing tempo information and depth information are changed by a tempo operator 50 and a depth operator 60 while musical sound waveforms are read from a waveform memory 10 by a waveform generating means 20 and swing playing is conducted.