Rattling of a vehicle-mounted equipment supported by a bracket is restricted. The attaching structure 1 for vehicle-mounted equipment has a housing 20 of vehicle-mounted equipment; an engagement arm 40 provided in the housing 20; a bracket 10 fixed to a vehicle body; and an engagement hole 13 formed in the bracket 10 to be engaged with the engagement arm 40, the engagement arm 40 is formed with a predetermined width along with one side edge 131 of the engagement hole 13 and is capable of being displaced in an engagement direction (the longitudinal direction of the center line Lm) to the engaged portion 135 formed on one side edge 131 of the engagement hole 131, the engagement arm 40 inserted into the engagement hole 13 being elastically engaged with the engaged portion 135 of the engagement hole 13 to attach the housing 20 of vehicle-mounted equipment to the bracket 10, wherein engagement members 50 and 50 are provided independently of the engagement arm 40 on both sides of the engagement arm 40 in the width direction thereof to be capable of being displaced in the width direction (the radial direction of the center line Lm), elastically engaging the engagement members 50 and 50 with the other side edges 133 and 134 of the engagement hole 13.