To eliminate machining difficulty, elements having various disadvantages and difficulty in fitting work of a seal material of a cylinder manufactured by a double bias sticking cloth formed by a chloroprene rubber laminated cloth taking the conventional tire cord as ground fabric.

One ply of vulcanized double-sided rubber laminated cloth taking as ground fabric a nylon plain weave cloth having 1260 denier or high and the number of placed yarns ranging from 13+2-2/in to 25+2-2/in the warp and the weft is used and joined taking 45-degrees to the vertical direction of the seal material as the vertical and horizontal directions of the rubber laminated cloth to form a cylindrical seal material, and the plural rubber laminated cloth pieces are pressed and heated to make a cylinder so that in bonding the longitudinal end parts thereof to each other, the end face of the end part is a slant face having substantially 45° and a reinforcement tape is coated on the slant face.