To provide a fluid supplying device for a motor-driven water pump, etc., capable of accommodating a control circuit in its housing and being embodied in a small-sized construction.

A motor-driven water pump 10 is structured so that a heat transmitting member 30 is tightly attached to a bulkhead 70 having a high thermal conductivity which partitions the inside of the housing 16 into a stator accommodation part 18 and a fluid passing part 44 and that a transistor base board 36 is installed in tight attachment to the heat transmitting member 30. Accordingly the heat generated by the base board 36 is transmitted to the bulkhead 70 through the heat transmitting member 30 and further to a cooling water flowing in the fluid passing part 44 to be released out together with the cooling water. Therefore, this requires no particular cooling device to allow the housing 16 to be designed in a small construction because no space is required for installation of cooling device.