A blow molding mold unit includes a pair of blow cavity split molds for forming a blow cavity, the blow cavity defining a shape of a side surface of a resin container, a bottom mold, and a jig configured to integrally support the pair of blow cavity split molds and the bottom mold. In a case where a direction extending from a shoulder portion or a body portion to a bottom portion of the resin container defined by the blow cavity is defined as a first direction, a direction in which the pair of blow cavity split molds are opened is defined as a second direction, and a direction orthogonal to the first direction and the second direction is defined as a third direction, the jig is provided at an end of the blow molding mold unit in the third direction.

A mold device includes: a plurality of sets of blow split molds that are disposed side by side in an opening and closing direction, in which one set of blow split mold, when closed, forms a blow molding female mold for blow molding, and, when opened, allows a molding product to be removed therefrom; and an interposed member that is interposed between one set of blow split mold of the plurality of sets of blow split molds and the other set of blow split mold of the plurality of sets of blow split molds in a case where the blow split mold is closed.