To provide a self-oscillation type oscillation circuit capable of obtaining a more accurate oscillation frequency.

The self-oscillation type oscillation circuit includes: a ring oscillator (1) whose oscillation frequency is varied in accordance with a bias current of the circuit; a frequency detection circuit (3) for generating a comparison result between a value determined according to the oscillation frequency of the ring oscillator (1); and a reference value, and a bias circuit (2) for controlling a bias current of the ring oscillator (1) on the basis of the comparison result. Since the oscillation frequency itself can be evaluated and feedback control for adjusting the oscillation frequency can be performed on the basis of the evaluation result, bias adjustment is automatically performed while always following the oscillation frequency of the ring oscillator (1) even when the oscillation frequency is varied and the variation of the oscillation frequency can be suppressed.