A passenger protection control device for effectively preventing an infiltration of water into the interior of a case without the use of a sealant includes: a printed circuit board; a connector; and a case that accommodates such that, while a connection end surface with a wire harness of the connector is exposed, the printed circuit board is isolated from the outside. The case is formed by: a box shaped cover in which the periphery of a ceiling wall is enclosed by side walls and a floor surface is opened; and a rear cover that plugs the floor surface of the cover. The connector is installed in an opening provided in the side wall of the cover. The rear cover has a first standing wall projecting so as to face a connector in the portion of the cover in which the connector is installed. The first standing wall of the rear cover has a planar region in a head top part. The planar region has an inclined surface having a falling gradient facing outwardly from the cover.