PURPOSE: To detect the component force of a tire rotating with a vehicle, by measuring the signal from a multiple component load cell rotating along with the tire.

CONSTITUTION: The title apparatus is equipped with a sampling means 2 for simultaneously sampling each component force signal from a multiple component force load cell rotating along with a tire and an angle-of-rotation signal showing the angle of rotation of the multiple component force load cell and a memory means 4 for storing each measured value obtained by the sampling means 2. The sampling and memory operations are repeatedly performed at every predetermined angle, at every predetermined time or at every angle-of-rotation. In such a case that the number of rotations of the tire and large and an operational processing means can not process measured values successively sent from the sampling means 2, each measured value is preliminarily stored in the memory means 4 anyway without performed operational processing and, after the finish of measurement, said stored value is operationally processed by the operational processing means.