To provide a circuit for generating sawtooth waves by charging and discharging a capacitor, which reduces a bottom voltage and variations of frequencies, which are caused by operation delay of a feedback circuit.

The sawtooth wave generating circuit includes a constant current source Iosc50 for supplying predetermined current, a resistance Rosc one end of which is connected to the constant current source Iosc50, the capacitor Cosc one end of which is connected to the other end of the resistance Rosc and the other end is grounded, a switching element 40 connected to both ends of the capacitor Cosc, and a feedback circuit 100 for switching the switching element 40 by using output of the capacitor Cosc. The circuit generates the sawtooth waves with a connection point between the constant current source Iosc50 and the resistance Rosc as an output terminal.