To provide an easy-unsealable inner partition carton, in which two commodities are separately housed in one carton to facilitate the takeout of the commodities, and a wider area for describing information, such as patterns and displays, is provided using a connection board.

A carton blank is assembled into the inner partition carton. According to the carton blank, a side board, a top board, a side board, a bottom board, a pasting board, the connection board, a partition board, and a gluing strip are formed consecutively via respective folding lines. A front lower board and a rear lower board are formed consecutively at both sides of the bottom board via folding lines, respectively. The carton is divided in two by the partition board. Breaking lines are formed on the top board and the front board, respectively, and a part of the top and front boards is teared along the top board and front board breaking lines to be made into opening/closing portion for opening the carton. The back of the gluing board is glued to the back of the bottom board, and a gluing part, which can be cut out, is formed on part of the connection board and the connection board and the top board are glued together at the gluing part.