PURPOSE: To provide an apparatus for automatically carrying out covering operation of a cover sheet so as to readily carry out a method for treating within shorter days in a tunnel in reduced labor of a worker.

CONSTITUTION: In this automatic covering device 20 for tunnel culture used for a frame body formed by covering a cover sheet 7 made of a resin on plural arch pipes 2 installed on bed soil at prescribed intervals, a resin tape arranged at prescribed intervals in the longitudinal direction of the frame body is connected from a ridge pole 3 to a rolling and unrolling shaft 5 and ridge pole 3 along the longitudinal direction of the frame body, a rolling and unrolling shaft 5, a weight 6, etc., are covered with the cover sheet 7 and fixed with a clamping device 8. Since the rolling and unrolling shaft 5 is fixed at nearly central part of the cover sheet 7 along longitudinal direction, when the cover sheet 7 is rolled up, the sheet is rolled by a handle 11 to upper direction simultaneously from the lower end and nearly central part of this cover sheet 7 and is connected to a driving supporting device 18 and, after setting a timer, connection to the driving supporting device is released and the sheet is unrolled in the direction reverse to the above direction and the rolling and unrolling shaft is loosend and dropped by own weight.