A heat medium relay unit, comprising: a heat exchanger related to heat medium that exchanges heat between a refrigerant in a refrigerant circuit in which the refrigerant is circulated by being discharged from a compressor provided in an outdoor unit and a heat medium, which is different from the refrigerant, in a heat medium circuit in which the heat medium is circulated and sent to a plurality of indoor units with a pump, the outdoor unit and the indoor units configured as separate housings; a plurality of heat medium flow control devices, with corresponding drive motors, that each control a flow rate of the heat medium sent to a use side heat exchanger of the corresponding indoor unit; a main body that houses the heat exchanger related to heat medium and the heat medium flow control devices; and heat medium flow switching devices (22,23) disposed so as to correspond to the indoor units, the heat medium flow switching devices (22,23) communicating an inlet side passage or an outlet side passage of the heat medium of each use side heat exchanger with the heat exchanger related to heat medium, characterized such that the heat medium flow control devices are disposed on a side of the body of the heat medium relay unit, defining the service side, the heat medium flow switching devices (22, 23) are disposed in heat medium pipes that are arranged in a direction substantially orthogonal to the service side and that are arranged parallel to each other, and are arranged so as to be offset with respect to a neighboring heat medium flow switching device (22, 23) relative to a same line that is orthogonal to the longitudinal direction of the heat medium pipes the heat medium flow control devices are connected such that one of pipe ports of each of the heat medium flow control devices is connected to a pipe port on a top side of the corresponding heat medium flow switching device (22, 23) or such that the one of the pipe ports of each of the heat medium flow control devices is connected to a pipe port on a bottom side of the corresponding heat medium flow switching device (22, 23), the drive motor of each of the heat medium flow control devices is installed on the service side, another one of the pipe ports of each heat medium flow control device is connected to a heat medium pipe that is positioned on a side opposite to the service side and that is oriented towards the corresponding indoor unit in the direction that is substantially orthogonal to the service side. a heat exchanger related to heat medium that exchanges heat between a refrigerant in a refrigerant circuit in which the refrigerant is circulated by being discharged from a compressor provided in an outdoor unit and a heat medium, which is different from the refrigerant, in a heat medium circuit in which the heat medium is circulated and sent to a plurality of indoor units with a pump, the outdoor unit and the indoor units configured as separate housings; a plurality of heat medium flow control devices, with corresponding drive motors, that each control a flow rate of the heat medium sent to a use side heat exchanger of the corresponding indoor unit; a main body that houses the heat exchanger related to heat medium and the heat medium flow control devices; and heat medium flow switching devices (22,23) disposed so as to correspond to the indoor units, the heat medium flow switching devices (22,23) communicating an inlet side passage or an outlet side passage of the heat medium of each use side heat exchanger with the heat exchanger related to heat medium, characterized such that the heat medium flow control devices are disposed on a side of the body of the heat medium relay unit, defining the service side, the heat medium flow switching devices (22, 23) are disposed in heat medium pipes that are arranged in a direction substantially orthogonal to the service side and that are arranged parallel to each other, and are arranged so as to be offset with respect to a neighboring heat medium flow switching device (22, 23) relative to a same line that is orthogonal to the longitudinal direction of the heat medium pipes the heat medium flow control devices are connected such that one of pipe ports of each of the heat medium flow control devices is connected to a pipe port on a top side of the corresponding heat medium flow switching device (22, 23) or such that the one of the pipe ports of each of the heat medium flow control devices is connected to a pipe port on a bottom side of the corresponding heat medium flow switching device (22, 23), the drive motor of each of the heat medium flow control devices is installed on the service side, another one of the pipe ports of each heat medium flow control device is connected to a heat medium pipe that is positioned on a side opposite to the service side and that is oriented towards the corresponding indoor unit in the direction that is substantially orthogonal to the service side.