To generate a triangular wave signal synchronizing with an external circuit.

A charge/discharge circuit 32 charges/discharges a capacitor C2 in which voltage of an end is fixed. A first comparator COMP1 compares output voltage Vout of the capacitor C2 with a first threshold voltage value Vmin, and outputs a first comparison signal S1 according to the comparison result. An edge detection circuit 34 detects an edge of a synchronous signal SYNC_IN which has a nearly half frequency of the triangular wave signal generated by a triangular wave generating circuit 30, and outputs an edge detection signal S4 which becomes a predetermined level for every detected edge. A charge/discharge control unit 40 refers the first comparison signal S1 output from the first comparator COMP1 and the edge detection signal S4 output from the edge detection circuit 34, changes over a charge/discharge condition of the charge/discharge circuit 32 according to level transition of these signals. The voltage of the capacitor C2 is outputted as a triangular wave signal Vosc.