PURPOSE: To provide a mounting structure of a cooling unit capable of easily performing a mounting operation, and capable of miniaturizing and simplifying the mounting parts.

CONSTITUTION: In amounting structure of a cooling unit 1 mounted on a heater unit 7 and a blower unit 5, a supporting part 27 having an inclined part 29 inclined upward along the mounting direction X of the cooling unit 1 and supporting the cooling unit 1 at a specified position, is provided at a blower unit 5. Further, one 33 of the engaging parts which are engaged with each other by the movement of the cooling unit 1 in the mounting direction X is provided on the cooling unit 1, and the other 35 of the engaging parts is provided on the heater unit 7. The engaging parts 33, 35 are engaged with each other to support the cooling unit l when the cooling unit 1 is at a specified position, and to prevent the cooling unit 1 from moving back and forth along the mounting direction X.