A rack type power source device includes a plurality of battery packs, a rack to house the plurality of battery packs being arranged, and a connector plate fixed to the rack at a far side in a direction in which the battery packs are inserted into the rack. The connector plate is provided with a plurality of connectors designed to be electrically connected to terminals of the plurality of battery packs. The connector plate includes a side wall that constitutes a part of a first-side wall of the rack, and a connector mount wall disposed at an inner position in the rack so as to form a depth difference from the side wall. The connector mount wall is provided with the plurality of connectors arranged corresponding to the battery packs housed in the rack.