An RF power module in which operating voltage is controlled by a control signal based on amplitude information includes a temperature detecting device which is provided over a semiconductor chip formed with an amplifying transistor or a semiconductor chip formed with a power source circuit; and a detector having a hysteresis characteristic which is provided over the semiconductor chip formed with the device or a different semiconductor chip, applies a bias to the temperature detecting device to compare the state of the device at two reference levels, outputs a signal indicating abnormality when judging that the temperature of the semiconductor chip formed with the temperature detecting device is above a predetermined temperature, and outputs a signal indicating normality when judging that the temperature of the semiconductor chip is below a second predetermined temperature lower than the predetermined temperature.