This invention relates to a system for mounting an underfloor electronic equipment to a rolling stock body having an underfloor storage portion formed under the floor in the longitudinal direction of the body as a portion of the body. The underfloor storage portion comprises a guidance tool for guiding and supporting the underfloor electronic equipment formed as a unit, a body-side connector corresponding to an electronic equipment-side connector formed to the electronic equipment, and a fixing tool for fixing the electronic equipment to the underfloor storage portion. The underfloor electronic equipment comprises a moving means guided by the guidance tool and the electronic equipment-side connector corresponding to the body-side connector. The electronic equipment can be moved by the guidance tool between a fixing position within the storage portion and a removal position outside the storage portion, the fixing tool used to fix the equipment to the fixing position where the equipment is electrically connected. The present invention facilitates maintenance and replacement of the electronic equipments and shortens operation time.