PURPOSE: To make the opening of a sliding door of opening of a garage being an entrance and exit larger than 1/2.

CONSTITUTION: In an automatic door for a garage opening and closing a wide entrance/exit of a garage accomodating two or more vehiles, two sliding doors l, 3 driven by a driving source such as a motor are arranged at both ends of an opening part 14 being the entrance/exit of the garage. Between two sliding doors l, 3 one or more intermediate sliding door 2 is arranged, at the sliding doors 1, 3, to move while it is engaged with engaging members 11a, 11b, 11c, lid. With these three or more sliding doors 1, 2, 3 the opening 14 is opened and closed.