In the switch MMIC of a compound semiconductor switching circuit device, the control resistance can be arranged near the common input terminal pad and output terminal pad to improve the electrostatic breakdown voltage and the surrounding impurity areas of the pad can be connected to protect the elements. However, a low control resistance and a parasitic capacitance protecting the elements can produce a pathway of high-frequency signals, which causes the problem of insulation deterioration. High resistance bodies are connected with protective elements near switching elements and with control resistances between adjacent protecting elements to avoid the high-frequency signal leakage even if a parasitic capacitance is caused by interruption of the high-frequency signal pathway and connectionof protecting elements, thus improving the electrostatic breakdown voltage and inhibiting the insulation degradation.