To control a temperature of an intake air of an engine and a temperature of a fuel according to a temperature in an intake duct, and exert desired engine output performance and fuel consumption performance.

This device comprises an intake box 16 accommodating an intake duct 17 of an engine 1 inside and having door means (door 19) capable of introducing a vehicle traveling air, a warm air pipe 14 capable of introducing warm air with temperature heightened by heats of exhaust air of the engine 1 in the intake box 16, a temperature sensor detecting a temperature in the intake duct 17, and control means (control unit 2) capable of controlling an introduction volume of the vehicle traveling air by the door means (door 19) and an introduction volume of the warm air by the warm air pipe 14 according to the temperature in the intake duct 17 detected by the temperature sensor.