To provide a variable speed device which does not require external circuit for the generation of a variable speed command and can automatically change set values for level discrimination and the number of revolutions and direction of rotation of a motor.

A variable speed device 1 incorporates a shutdown discriminating section 13 which generates operation/stop command to a motor, by discriminating the level of analog signals inputted from the outside. The device 1 also incorporates a calendar function for switching the discriminated level, according to the season, month and day, time, etc., and the number of revolutions and direction of rotation of the motor.