PURPOSE: To provide an open/close direction-variable flapper which can easily set its open/close direction, can improve its reliability and durability without deteriorating its hermetic performance and can surely check each person by setting two or more positions for attachment of a flapper unit.

CONSTITUTION: Two or more positions are set for the spaces, holes, etc., where a flapper unit 1 is attached, and the attachment angles of a lift gate, etc., are varied to a flapper main body. Meanwhile, three modes are set for the open/ close direction of the flapper against a passing person, etc., that is, a standard mode, an up-down mode where the attachment angle is changed by 90 degrees and an advancing direction oblique dot mode tilted to the standard open/close direction at about 45 degrees. And, the cover of the unit 1 is separated from the main body, and a cover 2 of a motive power source part uses a hard and stiff material together with a cover 3 of an open/close part using a soft and flexible material with high elasticity. Furthermore, the hermetic performance is improved for a lower cover 4, and the gaps are eliminated among the bottom hole of the cover 4, the attachment part of the unit 1 and the cover 3.