A battery stack plate including a housing is provided. The housing has a first sub housing and a second sub housing. Each of the first and second sub housings has a coupling portion coupling the first and second sub housings to each other. The coupling portion includes a protruding portion provided on a coupling plate side face on which the first sub housing and the second sub housing are coupled to each other, and a recessed portion provided on the coupling plate side face at a position shifted from the protruding portion in the up-down direction.