A filter plug having a dual structure comprising filter element A made from a crimped long filter tow in a form of a plug, filter element B, joined to said A, prepared by wrapping a core material consisting of a long fiber tow in a sheet-formed product having grooves which is formed from a material having an air permeability of 8 liters/minute or less and an air permeable wrapping paper and/or a wrapping paper with perforated openings on its periphery which is wrapping therein said filter elements A and B so that the outer grooves parts of the sheet-formed product pass through in the longer direction of the filter plug.