Filter and manufacturing method therefor

A filter comprising:

• a first case member and a second case member that are made of a synthetic resin and are mutually joined at a joining end of said first case member and a joining end of said second case member to form a filter chamber;
• and
• a filter element including a filtering medium and a holding frame made of a synthetic resin which holds a peripheral portion of said filtering medium and is held between the joining end of said first case member and the joining end of said second case member,
• wherein a weld portion formed by laser light is provided at a contact area extending in a joining direction between said holding frame of said filter element and at least one joining end of said joining end of first case member and said joining end of second case member,
• wherein one of said joining end of said one case member and said holding frame of said filter element is provided with a convex portion that protrudes in the joining direction, the convex portion including a tapered face angled in the joining direction, and the other of said joining end of said one case member and said holding frame of said filter element is provided with a concave portion that engages with said convex portion, the concave portion including a tapered face angled in the joining direction,
• wherein the tapered face of the convex portion and the tapered face of the concave portion engage at an inner side surface of an engagement portion between said convex portion and said concave portion with a space defined between a tip face of said convex portion and a bottom face of said concave portion, and
• wherein said weld portion is provided at an outer side surface of said engagement portion between said convex portion and said concave portion opposite said inner side surface of said engagement portion.