An AC-AC converter circuit adapted to convert an AC voltage into a further AC voltage, wherein a Z source circuit, a T source circuit (20) or a Γ source circuit (20) is provided between a rectifier circuit that is configured to rectify the AC voltage and an inverter circuit that includes an inverter circuit switching element and that is configured to generate the further AC voltage, a step-down circuit that includes a step-down circuit switching element, and a diode or a further switching element, is provided between the rectifier circuit and the Z source circuit, the T source circuit (20) or the Γ source circuit (20), and the AC-AC converter comprises a control circuit configured to control the step-down circuit and the inverter circuit, characterized in that the control circuit is configured to use, for control, a first operation mode in which the step-down circuit switching element is on and the inverter circuit switching element is off, a second operation mode in which the step-down circuit switching element is off and the inverter circuit switching element is off, and a third operation mode in which the step-down circuit switching element is on and the inverter circuit switching element is on; and the control circuit is configured to perform control in a step-down operation so that the first operation mode and the second operation mode are periodically repeated, and in a step-up operation so that the first operation mode and the third operation mode are periodically repeated. a Z source circuit, a T source circuit (20) or a Γ source circuit (20) is provided between a rectifier circuit that is configured to rectify the AC voltage and an inverter circuit that includes an inverter circuit switching element and that is configured to generate the further AC voltage, a step-down circuit that includes a step-down circuit switching element, and a diode or a further switching element, is provided between the rectifier circuit and the Z source circuit, the T source circuit (20) or the Γ source circuit (20), and the AC-AC converter comprises a control circuit configured to control the step-down circuit and the inverter circuit, characterized in that the control circuit is configured to use, for control, a first operation mode in which the step-down circuit switching element is on and the inverter circuit switching element is off, a second operation mode in which the step-down circuit switching element is off and the inverter circuit switching element is off, and a third operation mode in which the step-down circuit switching element is on and the inverter circuit switching element is on; and a first operation mode in which the step-down circuit switching element is on and the inverter circuit switching element is off, a second operation mode in which the step-down circuit switching element is off and the inverter circuit switching element is off, and a third operation mode in which the step-down circuit switching element is on and the inverter circuit switching element is on; and the control circuit is configured to perform control in a step-down operation so that the first operation mode and the second operation mode are periodically repeated, and in a step-up operation so that the first operation mode and the third operation mode are periodically repeated. in a step-down operation so that the first operation mode and the second operation mode are periodically repeated, and in a step-up operation so that the first operation mode and the third operation mode are periodically repeated.