A relay device comprises a base, a pin, and an outer cap. A gap is arranged at a peripheral of the base. The pin has a convex plate and assembled to the gap of the base and one end thereof is protruded from the gap. The convex plate is covered/shielded the gap. The outer cap includes a receiving groove. A notch of the receiving groove is covered the base and the pin. A paste is applied among the peripheral of the base, the convex plate of the pin, and the notch of the receiving groove for fastening. The gap arranged at the peripheral of the base is providing the pin for assembling without directional limitation and advantageous to once assembly of the base and the pin in an automatic machine so as to simplify the manufacturing process of the relay device.