To provide an air-conditioning apparatus capable of achieving energy saving. In an air-conditioning apparatus, a first housing (an outdoor unit) that accommodates a compressor and a heat source side heat exchanger; a second housing (a heat medium relay unit) that accommodates a heat exchanger related to heat medium, an expansion device, and a pump; a third housing (a heat medium regulating unit) that accommodates a first heat medium flow switching device, a second heat medium flow switching device, and a heat medium flow control device; and a fourth housing (indoor unit) that accommodates a use side heat exchanger have separately different casings.