A bearing oil feeding amount is appropriately controlled with respect to specifications of a discharge pressure (bearing load) and a rotation speed. A gas compressor has: a compressor main body that compresses gas and has a rotor; a bearing for supporting the rotor onto a compressor main body casing; an oil case that stores a lubricating oil to be supplied to the bearing; a lubricating oil pipe through which the lubricating oil is circulated from the oil case to the bearing; an oil pump that pumps the lubricating oil from the oil case to the bearing via the lubricating oil pipe; a flow amount control means for adjusting an amount of lubricating oil that circulates through the lubricating oil pipe; an electric motor that supplies power to the rotor; an inverter that outputs a rotation frequency of the electric motor; a pressure sensor that detects the discharge pressure of the compressor main body; and a control unit that determines a lubricating oil supply amount to the bearing on the basis of the load on the bearing corresponding to the pressure detected by the pressure sensor and the rotation speed of the rotor corresponding to the rotation frequency output by the inverter, and that controls the flow amount control means on the basis of the lubricating oil supply amount.