The present invention comprises a housing joined to a transmission having an ATF (automatic transmission fluid) inside to draw the ATF inside or discharge the ATF; and a heating element joined to the housing to heat the ATF flowing inside the housing by generating heat in accordance with power supply. Thus the present invention is capable of promptly heating the ATF using power supply and keeping the generated heat in the housing, thereby improving fuel efficiency by enabling the ATF to have a viscosity in a normal range at an early stage.COPYRIGHT KIPO 2014