A temperature calculation system for a motor uses a thermal equivalent circuit wherein a yoke is disposed to be fixed onto an inner circumferential surface of a housing of the motor, a coolant chamber in which a coolant flows is formed in a circumferential direction in the housing, and the thermal equivalent circuit including thermal resistance coefficients and temperatures is used. An endothermic amount of the coolant flowing in the coolant chamber of the housing is calculated by using an average temperature of the housing and a preset equation.