The present invention provides a system for evaluating motor control function in the brain. This system is for evaluating the motor control function in the brain of a subject from the electromyogram (EMG) data of joint prime movers and the data on the position, velocity and acceleration of the joint, wherein both of the data have been obtained by measuring a target-tracking movement performed by the subject with a motion measurement unit that tracks a moving target, the system comprising the following means (a) to (c): (a) means for separating the frequencies of the EMG data and the frequencies of the data on the position, velocity and acceleration into a plurality of frequency components; (b) means for determining the ratio of viscosity coefficient to elastic coefficient (B/K ratio) for each of the frequency components by applying the EMG data and the data on the position, velocity and acceleration to a specific movement equation; and (c) means for evaluating the causal relationship between the motor control function in the brain and the target-tacking movement using the B/K ratio as an index.