To provide an instrument control apparatus, a function restriction method for the instrument control apparatus, and a function restriction system which can set a proper and safe function restriction level on the basis of the state of a field instrument related to process control.

An instrument control apparatus 200 that performs instrument control for a field instrument arranged in a system for performing process control and can perform function restriction for any of a plurality of control functions for executing the instrument control comprises: an acquisition means 210 for acquiring a state signal related to the process control out of the field instrument states; and a setting means 220 for setting a function restriction level on the basis of the state signal acquired by the acquisition means 210.