A connector (1) according to the present invention includes: an elastic valve body (3) which includes a top face (10) on which a slit (9) is formed and a bottom face (11) on an opposite side of the top face (10) and a holding section (48) which is in contact with the top face (10) and the bottom face (11) of the elastic valve body (3) and holds the elastic valve body (3), the holding section (48) is provided to surround the slit (9), and the elastic valve body (3) includes a peripheral section (14) which is positioned on an outer side than a position thereof being held by the holding section (48) when the elastic valve body (3) is viewed from the top face (10) side, and a volume (V1) of the peripheral section (14) in a state in which the elastic valve body (3) is held by the holding section (48) is larger than a volume (V2) of the peripheral section (14) in a state in which the elastic valve body (3) is not held by the holding section (48).
