To provide a closure tool capable of allowing a meshing tool of a bag body to be easily and surely meshed, by sequentially meshing recesses with projections of the meshing tool along an opening to fit them to each other by laterally moving the closure tool.

A closure tool for closing a meshing tool of a bag body, includes an upper presser part and a lower presser part protrudingly formed in the same direction from a grip part. A length of each of the upper presser part and the lower presser part is at least longer than a length from one end of the bag body to the meshing tool. At least a part of a gap between the upper presser part and the lower presser part is at least narrower than a width of the meshing tool of the bag body in which the recesses are not meshed and contacted with the projections.