An assembly structure of an electronic control unit and a coil assembly of a solenoid valve for an electronic brake system connected to the electronic control unit having a printed circuit board and applying power to the solenoid valve. The coil assembly is penetrated to allow an upper portion of the solenoid valve to be fitted thereinto, and includes a cylindrical bobbin provided with a coil and a coil case. The electronic control unit is provided with a housing having an insertion groove and joined to the hydraulic control unit, the printed circuit board being disposed spaced apart from the coil assembly, and the housing is provided with an elastic member having one end contacting the printed circuit board and the other end contacting the coil case. The elastic member is configured with a coil spring to produce different elastic forces.