PURPOSE: To provide enough rigidity and strength to a center console box, by supporting the box by means of a supporting member extending between an air conditioning unit and a floor.

CONSTITUTION: A supporting member 4 is positioned extending between an upper face C2 of a tunnel part C1 in a floor C and an air conditioning unit 3 located below an instrument panel A at the front of a car room and secured to a dash panel B, and the front of a center console box 5 or a rise part 54 is mounted to the supporting member 4. At the rear of the center console box 5, its side parts 55 at both sides of a horizontal part 52 are tightened against a support bracket 57, secured to the upper face C2 of the floor C by means of bolts 56, by the use of bolts 58. At the front thereof, the side parts 55 cover the supporting member 4 in a manner to straddle a reinforcing flange 46 and a mounting flange 47, and are tightened by means of bolts 59 for installation.