PURPOSE: To reduce the power supply voltage dependency of an oscillation frequency by supplying a power supply voltage individually to high and low potential bias generation circuits included in a bias generating part, respectively.

CONSTITUTION: An oscillation circuit is provided with an oscillation part 9 which generates and outputs an oscillation signal, a bias generating part 1 which outputs high and low potential bias voltages, and a current supply part 6 which supplies a driving current for the oscillation part 9 by receiving both voltages. The bias generating part 1 is provided with a bias voltage generation circuit which generates and outputs the high potential bias voltage by receiving the supply of a prescribed power supply voltage VDD and including a PROS transistor 2 and a resistor 3. Furthermore, a bias voltage generation circuit which generates and outputs the low potential bias voltage by receiving the supply of the power supply voltage VDD and including a resistor 4 and an MHOS transistor 5 is provided individually. As a result, the power supply voltage dependency of a current between the drain and source in the saturation area of an NMOS transistor 8 in the current supply part 6 can be reduced. and the power supply voltage dependency of the oscillation frequency can be improved.