A gas compressor comprising: a compressor main body that is configured to compress a gas; a drive source that is configured to drive the compressor main body; a controller that is configured to control a rotation speed of the drive source in accordance with a discharge pressure of the compressor main body; and a temperature detector that is configured to detect a temperature of a discharge gas of the compressor main body, the gas compressor configured to perform no-load operation in which the rotation speed of the drive source is a lower limit rotation speed, when the discharge pressure reaches an upper limit pressure higher than a set pressure, wherein when detecting that the temperature detected by the temperature detector is equal to or lower than a predetermined temperature during the no-load operation, the controller is configured to cause the lower limit rotation speed of the drive source to be a lower limit rotation speed at which the temperature of the discharge gas is higher than the predetermined temperature, the lower limit rotation speed being higher than a lower limit rotation speed at which the detected temperature is higher than the predetermined temperature, characterized in that the controller is configured to wait to start detection for a predetermined period of time before detecting that the temperature detected by the temperature detector is equal to or lower than the predetermined temperature, the gas compressor further comprising at least one of a suction throttle valve that is configured to control an intake amount of the compressor main body and an gas relief valve disposed in a discharge line (10a, 10b, 10c) of the compressor main body to release the discharge gas, wherein the controller is configured to cause the suction throttle valve to be closed and the gas relief valve to be open during the no-load operation, and when the discharge pressure of the compressor main body reaches a lower limit pressure which is lower than the upper limit pressure and is equal to or higher than the set pressure, the controller is configured to switch to load operation in which the throttle valve is opened and the gas relief valve is closed, at the lower limit rotation speed of the no-load operation. a compressor main body that is configured to compress a gas; a drive source that is configured to drive the compressor main body; a controller that is configured to control a rotation speed of the drive source in accordance with a discharge pressure of the compressor main body; and a temperature detector that is configured to detect a temperature of a discharge gas of the compressor main body, the gas compressor configured to perform no-load operation in which the rotation speed of the drive source is a lower limit rotation speed, when the discharge pressure reaches an upper limit pressure higher than a set pressure, wherein when detecting that the temperature detected by the temperature detector is equal to or lower than a predetermined temperature during the no-load operation, the controller is configured to cause the lower limit rotation speed of the drive source to be a lower limit rotation speed at which the temperature of the discharge gas is higher than the predetermined temperature, the lower limit rotation speed being higher than a lower limit rotation speed at which the detected temperature is higher than the predetermined temperature, characterized in that the controller is configured to wait to start detection for a predetermined period of time before detecting that the temperature detected by the temperature detector is equal to or lower than the predetermined temperature, the gas compressor further comprising at least one of a suction throttle valve that is configured to control an intake amount of the compressor main body and an gas relief valve disposed in a discharge line (10a, 10b, 10c) of the compressor main body to release the discharge gas, wherein the controller is configured to cause the suction throttle valve to be closed and the gas relief valve to be open during the no-load operation, and