A signal generation unit 2, a DA converter 3, variable attenuators 40, 42, 44, and 46, a measurement unit 6 that detects a level of the signal attenuated by the variable attenuators 40, 42, 44, and 46 and passed through one or more semiconductor components, a switch 48 that switches between an Internal path through which the signal attenuated by the variable attenuator 40, 42, 44, and 46 is transmitted to the measurement unit 6 and an External path through which the signal attenuated by the variable attenuator 40, 42, 44, and 46 is output from an output terminal 10, and a control unit 7 that obtains a correction value of an attenuation amount of the variable attenuators 40, 42, and 44 with the Internal path and obtains a correction value of an attenuation amount of the variable attenuator 46 with the External path.