To provide a crystal oscillation circuit low in current consumption and stably short in oscillation start time. A crystal oscillation circuit is equipped with a crystal vibrator, a feedback resistor, a bias circuit, a constant voltage circuit, and an oscillation inverter configured by a constant current inverter. The oscillation inverter is configured so as to be controlled by currents based on input signals from the bias circuit and the crystal vibrator and driven by an output voltage of the constant voltage circuit.