SEAL MEMBER, AND PLUG TUBE SEAL STRUCTURE FOR ENGINE

A seal member (3) is disposed between a cylinder head cover (1) in which an ignition plug mounting hole (1a) is formed and a plug tube (2) which is inserted in the ignition plug mounting hole (1a). The seal member (3) is provided with: a base section (31) configured to be elastically deformable and inserted into the ignition plug mounting hole (1a); a protrusion section (32) formed so as to protrude outward in the radial direction from the outer peripheral surface of the base section (31) and engaging with a groove (12b) formed in the inner peripheral surface of the ignition plug mounting hole (1a); a seal lip section (33) in elastic contact with the outer peripheral surface of the plug tube (2); and a grip section (34) formed between the base section (31) and the seal lip section (33) and protruding downward from the ignition plug mounting hole (1a).