A housing-securing unit for a vehicle includes: a housing in which a circuit board is to be housed; and a bracket through which the housing is mounted to the vehicle. A holding pin having a column shape is provided on a side surface of the housing. The bracket has a side support component in which a through hole is formed for fitting the holding pin. The holding pin has an inclined approach surface having a height that is increased as extending in an assembling direction, and a holding surface formed to regulate the side support component from moving in the assembling direction and to oppose an inner peripheral surface of the through hole when the holding pin is fitted to the through hole. A height of a top part of the holding surface is more than or equal to a height of a top part of the inclined approach surface.