A closing jig for a green honeycomb molded body includes closing protrusions which are arranged at positions corresponding to regular hexagonal cells and are inserted into the regular hexagonal cells to weld partition walls to each other for closing. Each of the closing protrusions includes a conical tip end portion that has a conical shape, and a triangular pyramidal base portion with a truncated triangular pyramidal shape having an apex angle larger than an apex angle of the conical tip end portion. The conical tip end portion has the conical shape with an acute apex angle. The triangular pyramidal base portion has the truncated triangular pyramidal shape having the large apex angle.