To provide a blow-molded product incorporated with a filter function part easily and efficiently by monolithically forming an air cleaner container as a blow-molded product and, at the same time, setting a filter in the container during blow-molding and, further, integrating both filter and container in one piece during blow-molding.

An air cleaner 1 as the air suction system part of an automotive engine has an air cleaner container part 2 which is blow-molded, an inlet part 3 and an outlet part 4, and an internally built-in filter structure 5. Air filtered by the air cleaner 1 enters the interior 1a on the inlet side of the air cleaner 1 from the inlet part 3 to be filtered by the filter structure 5. Next, the cleaned air is supplied to the engine or the like passing through a duct or the like from the outlet part 4 after the air flows through the outlet side interior 1b of the air cleaner 1. A filter 5a with a filter function has a locking part 5b which fits partially into the air cleaner container part 2, preferably all around the part 2. The filter 5a is integrated with the air cleaner container part 2 through the locking part 5b.