In a circuit substrate of an electric water pump, a Hall IC can be mounted on a circuit substrate at an optimum position in a stable and durable state. The electric water pump includes a motor housing, a stator constituted by a stator core covered by a resin insulator and a coil, a circuit substrate, a holder 6 mounted on the circuit substrate, and a Hall IC mounted on the holder. A holder accommodation portion, into which the holder is inserted, is formed in the insulator, the stator is disposed in and fixed to the motor housing, the circuit substrate is appropriately mounted on the motor housing, and the holder 6 is inserted into and supported by the holder accommodation portion.