PURPOSE: To increase cooling effect and reduce noises to a minimum in a structure mounting cooling fan module.

CONSTITUTION: A cooling fan module 20 has a finger guard body 10 at a ventilation hole. In a mounting structure, the finger guard body 10 is changeable into a closing state, in which the finger guard body 10 is extended almost all over the ventilation hole and an opening state, in which the finger guard body 10 is folded to an edge part of the ventilation hole opposite to an edge on the insertion side to a main unit body 30. In addition, the main unit body 30 has an operating member 40 at a module insertion hole 31. When, a cooling fan module 20 is inserted, the operating member 40 is fitted to a front edge of the finger guard body 10 so that the finger guard body 10 changes into the opening state by force. On the contrary the finger guard module body 10 changes into the closing state by force when the cooling fan module 20 is removed.