A crosstalk correction coefficient of a multi component force detector provided in a rolling resistance testing machine is calibrated. A method of calibrating a multi component force detector provided in a rolling resistance testing machine including a spindle shaft to which a tire is attached, a running drum with a simulation road surface on which the tire is pressed, and a rotation torque meter provided in a rotation shaft of the running drum; in which, in performing a process of calculating a force acting on the tire from a measurement value of the multi component force detector by using a crosstalk correction coefficient that corrects an influence of crosstalk occurring in the multi component force detector, the crosstalk correction coefficient is calibrated by using a rolling test data including a rotation torque measured by the rotation torque meter and a force measured by the multi component force detector.