To provide an easily mountable swing lock device of an overhang sliding door capable of making a floor barrier-free.

This swing lock device comprises an engaging member 10 installed on the lower surface of the overhang sliding door 1 at the intermediate part of the sliding door in the opening and closing direction B, a swing lock member 11 having an engaged groove 25 formed along the opening and closing direction B of the sliding door so that the engaging member 10 is engaged movably in the opening and closing direction B, limiting the lateral swing of the overhang sliding door 1 in the accessing direction C, and disposed on the lower side of the overhang sliding door 1 when the overhang sliding door 1 is at the open position, and a support member 12 disposed on the front end lower side of the overhang sliding door 1 in the closing direction D at the open position, fixedly mounted on a floor 8, and supporting the swing stop member 11 movably in the opening and closing direction B of the sliding door.