Connected part seal structure, and seal member

A connected-part seal structure configured to couple a first connected part and a second connected part through a seal member, wherein both or one of a connection end face of the first connected part and a connection end face of the second connected part includes:

• a passage wall including an open end that opens in the connection end face;
• an annular protrusion annularly extending along an outer periphery of the open end of the passage wall, the annular protrusion protruding in an axial direction of the passage wall;
• and
• an inner mounting groove provided inside the annular protrusion in a radial direction, and
• the seal member has an annular shape and includes an annular groove in both or one of end faces, in which the annular protrusion is press-fitted,
• wherein the inner mounting groove includes an inner tapered part provided inside a base end part of the annular protrusion in the radial direction and at a sharp angle to the annular protrusion, the inner tapered part being continuous with the passage wall,
• the seal member includes an inner peripheral surface including an inner pressure-contact tapered part formed along an end portion positioned close to the end face in which the annular groove opens, the inner pressure-contact tapered part being slanted corresponding to the inner tapered part, and
• the inner pressure-contact tapered part has a taper angle smaller than a taper angle of the inner tapered part.