A gap blocking mechanism (1) includes: an engine cover (2); a cover (3) for a cylinder head cover that is disposed on a front side of a cylinder head cover (920) disposed at a predetermined distance from a back side of the engine cover (2); and a blocking member (4) that blocks at least a part of a gap between the engine cover (2) and the cover (3) for a cylinder head cover, and that is formed integrally with any one of the engine cover (2) and the cover (3) for a cylinder head cover and elastically contacted with an elastic member (21) included in the other thereof using elastic contact force of the elastic member (21). The blocking member (4) is provided between a heat source (93) on one side and a member (940, 941) to be protected on the other side.
