A solid state relay has a first external connection terminal which is conductive with one end of a main switching element, and a second external connection terminal which is conductive with another end of the main switching element, and is used with a load and a power source connected in series between the external connection terminals. A third external connection terminal is disposed in the solid state relay. The third external connection terminal is connected to the second external connection terminal via a capacitor. The load and the power source are connected in series between the first external connection terminal and the second external connection terminal, and a node of the load and the power source is connected to the third external connection terminal, thereby allowing the resistance of the load and the electrostatic capacitance of the capacitor to constitute an RC filter circuit for preventing noise leakage. Therefore, a solid state relay is obtained in which less EMI noise (noise terminal voltage) is generated, and which can be produced without especially increasing the cost and the size as compared with a relay of the conventional art.