Abstract: An interposition structure interposed between substrates and capable of guiding the insertion of a connection pin for electrically connecting the substrates to each other, whereby the connection pin can be inserted properly even in cases where the substrates to be connected or other members have a dimensional error caused during production thereof, a positioning error or the like. The interposition structure has an interposition body in which a through hole is formed such that connection pin inlet and outlet portions thereof each have an inner diameter gradually increasing in a direction from the inner part to the corresponding outer open end thereof, and also has a positioning protuberance provided on the underside of the interposition body.