A collision sensor 1 is mounted on a pedal bracket 2 which are supported by a front frame 4, a front mount rail 5, and a reinforce 8 which are all located in front of the cab. The collision sensor 1 is connected through a cable 24 to the gas generator 21 of a pretensioner seat belt 16 and to the inflator 23 of an air bag 17. The pedal bracket 2, being high in rigidity, senses a shock wave well, and is scarcely damaged at the time of a collision. Since it is not exposed directly in the air, it is high in weather resistance, and is proper in maintenance because it is located at the position to which the hand can be readily extended. Thus, at the time of a collision, the degree of injury to the passenger is minimized.