ELECTRICAL CONNECTION BOX

An electrical connection box includes a casing and a cover member. The cover member includes: a cover-member main body; a restriction piece arranged along an arrangement direction with respect to a pair of locking pieces; and a rigid part that is disposed with a space provided with respect to the cover-member main body in an orthogonal direction and is extended toward the orthogonal direction. The casing includes: a pair of restriction reception parts opposing to respective ends in the arrangement direction of a pair of the restriction pieces in a state in which the cover member is fitted to the casing; and a rigid reception part having a rigid-reception-part projecting wall part located between the rigid part and the cover-member main body in a state in which the rigid part is inserted and the cover member is fitted to the casing.