An encrypted control system that use fog computing and is implemented in a real-world industrial context is the subject of this letter. The system that was created uses multiplicative homomorphic encryption to hide controller gains and signals via communication lines, protecting them from eavesdropping assaults. The designed system is confirmed to be feasible for position servo control of the motor-driven stage by experimental validation, which examined processing time, parameter variation, and performance deterioration. Whether or not the plant parameters change, the created system retains its stability even after encrypting the controller gains and signals. Increasing the length of an encryption key really improves control performance, even if it increases processing time.