To provide an oscillation circuit securing output symmetry without generating self-oscillation.

In a Colpitts crystal oscillation circuit, a transistor MP1 for raising a feedback bias voltage of a CMOS inverter INV1 and a transistor MP2 to be turned on when there is no oscillation output are connected in series between an output side (node N1) of the CMOS inverter INV1 and a power source VDD. The node N1 is pulled up to voltage higher than VDD/2 at the beginning of power on. When the normal oscillation starts and the voltage of a node N3 reaches a prescribed value, the transistor MP2 is turned off and a pull-up of the node N1 is released. A CMOS inverter INV2 for inverting the output of the CMOS inverter INV1 is connected. An AND circuit AND1 is connected to a node N2 of the output side. When the normal oscillation starts and the voltage of the node N3 reaches a prescribed value, a gate of the AND circuit AND1 is opened and oscillation signal of the node N2 is output to an output terminal OUT after delay of a delay circuit DL1.