To provide a triangular wave oscillation circuit which stably oscillates a triangular wave having a desired frequency even if it has a built-in capacitor.

The triangular wave oscillation circuit has: a built-in capacitor 16 having an output terminal; constant current sources 12, 13 for charging and discharging the built-in capacitor 16; a current setting circuit 11 for setting current values of the constant current sources 12, 13: a monitoring circuit 17 for switching the charging and discharging of the built-in capacitor 16 by detecting a voltage of the built-in capacitor 16; a reference clock generating circuit 19 for creating a reference pulse signal of the frequency of the desired triangular wave; and a current adjusting section 18 for varying a current value to be set by the current setting circuit 11 on the basis of the transition timing of the reference pulse signal and the timing of a signal to be output by the monitoring circuit 17 to the current adjusting section 11 when the built-in capacitor 16 has a predetermined voltage.

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