PURPOSE: To provide a sealing method, which suppresses the consumption of sealing agent, achieves the light weight of the entire body and can seal the circuits constituted on both substrates excellently, as the sealing method for a hybrid integrated circuit, which is formed in a hollow case shape by assembling two substrates with a frame body under the state wherein the circuits of the respective substrates face to each other.

CONSTITUTION: As a sealing agent for sealing the surfaces of substrates 2a and 2b, a sol-state viscous sealing agent, which forms a sealing layer by hardening, is used. The sealing layer 11 is formed on the surface of one substrate 2b located at lower side of both substrates 2a and 2b through an injecting hole 8c, which is provided at a base end part 8a of a connector 8. Then, both substrates 2a and 2b are inverted upside down, and the sealing layer 11 is formed on the surface of the other substrate 2a.