Method for broadening width of existing bridge without temporary road

A method for widening the existing bridge is provided, which enables to widen the existing bridge while not affecting transit of vehicles and reduces the whole construction period. A method for widening the existing bridge comprises: a step of installing an anchor-shape board by raising the slab of the existing bridge; a step of pouring new concrete after reinforcing the upper side of pier coping(1) of the existing bridge; a step of enlarging the pier column(2) of the existing bridge; a step of enlarging the pier coping of the existing bridge; a step of installing new slab on the upper both sides of the expanded bridge pier coping; and a step of disjointing anchor-shape board.