NOVELTY - The electricity storage module (100a,100b) has a battery case that includes a cooling medium intake port, a cooling medium outlet port and a cooling flow passage through which battery cells housed in a parallel array pattern are cooled. A duct is detachably mounted at the cooling medium intake port of the battery case. The battery case includes an engagement contact portion located inside the battery case. The duct includes an engaging unit that engages with the engagement contact portion of the battery case.    USE - Electricity storage module for electricity storage device e.g. lithium-ion battery device, nickel-metal hydride battery device of in-vehicle power supply system for use in electric vehicle such as railway vehicle e.g. hybrid train, public transportation vehicle e.g. bus, freight vehicle e.g. truck and industrial vehicle e.g. battery operated forklift truck. Can also be used in fail safe power supply system for computer system or server system and power source system used for on-site industrial power generation.    ADVANTAGE - High level of safety is assured for the in-vehicle electrical machine system by controlling the electrical connection between the electricity storage device and the inverter device through the relay structure. Better strength is assured for the electricity storage module unit by the controller functioning as the holding unit. Since the changing of the overall structure of the case portion for of flow rate/inflow direction adjustment can be eliminated and the case portion can be standardized, better productivity is assured. Since the entire case portion can be eliminated from replacing when the cooling medium intake duct is damaged, the maintenance and production cost can be reduced. As the space inside and outside the case portion can be separated from each other with the higher level of reliability, better product reliability can be assured. The short-circuiting between the covering plate and the conductive units can be prevented by preventing the conductive unit from contacting the covering plate. The wiring error can be prevented by setting the length of the connecting line to the value equivalent to the distance between the connector terminals.    DESCRIPTION OF DRAWING(S) - The drawing shows a circuit block diagram of the electricity storage system equipped with electricity storage module.    Motor generator (10)    Inverter device (20)    Driver circuit (22)    Vehicle controller (30)    Electricity storage modules (100a,100b)