To provide a mounting structure of an engine cover for facilitating assembling work of the engine cover and for simplifying a construction of a die for an intake manifold.

In the mounting structure of the engine cover, a bolt T1 inserted in a bolt hole 21a of the engine cover 20 is screwed in a boss 13 of the intake manifold 10 of an engine and the engine cover 20 is thereby attached above an intake manifold 10. An axis 21L of the bolt hole 21a is directed upward and tilted forward of a vehicle and the boss 13 is projected upward and tilted forward of the vehicle so that they coincide with a drawing direction of the die for molding the intake manifold 10.