To provide an orifice reducer which can be inserted into a container dimensions or shapes of which are uneven at a neck opening section.

The orifice reducer (10) is provided with a crumple area suitable for an extrusion blow molded bottle having an uneven surface finish section, namely, the area that is crushed and corrugated and has a peripheral wall (34) having a plurality of thin areas (36) extending in the upper and lower directions. The areas (36) are symmetrically spaced out along the wall (34). The areas (36) are deformed when the orifice reducer (10) is inserted inside a bottleneck (16), expecting the unevenness of the bottle surface finish section, thereby allowing the orifice reducer to be easily inserted inside a standard extrusion blow molded bottle.