To provide a hydraulic rodless cylinder drive type horizontally sliding gate that can terminate a series of operations automatically and rapidly in an extremely reliable manner.

A horizontal and semi-hermetic type hydraulic rodless cylinder enclosing body is provided in a door body of the horizontally sliding gate, and the opposite side end to an opening 11 is fixed to a tide embarkment 10. A hydraulic rodless cylinder 2 with its entire length equivalent to about 60% of the whole length of the door body is held in a movable state to the enclosing body. A DC motor driven miniature hydraulic unit 7 is provided, and the upper part of a hydraulic rodless cylinder outer chain is fixed to the enclosing body, while a door body connecting member 9 is fixed to the lower part. Work of placing the door body on a rail 14 through wheels 6 is performed first, and then horizontal moving work can be automatically attained with the hydraulic rodless cylinder. Quick power-saving work with no anxiety about causing malfunction is thereby attained with a battery power supply of a light car.