PURPOSE: To reduce the moment of inertia of a driving part by reciprocating a wave production plate linearly through a wound transmission member.

CONSTITUTION: When a motor 6 is driven, a belt 5 reciprocates as shown by arrows K and L by constant distance and the wave production plate 8 reciprocates horizontally on a guide rail 18 as shown by arrows M and N by constant distance through a connector 15 to produce waves 21 on a water surface. The rotating speed of the motor 6 is detected by a tachometer 20, whose speed signal is fed back to a controller 9 to control the rotating speed of the motor 6. The height of the waves 21 is detected by a wave height meter 19, whose signal is fed back to the controller 9 to control the rotating speed and direction of the motor 6. The moment of inertia of the belt 5 becomes extremely small because the belt 5 is made of synthetic resin and lightweight and the wave production plate 8 is mounted on the guide rail 18 through sliding rollers 16.