Vertical stiffeners are connected to deck plates to prevent out-plane-buckling of webs in steel girder bridges with steel plate decks. When wheel loads are located close to stiffeners, high stress concentration is prone to occur at the edge of the stiffener because the stiffener restricts deformation of the deck plate. In recent years, many cracks have been observed there. Therefore, a method for reinforcing and/or repairing the connection between the deck plate and the stiffener is essential. In this paper, the method is proposed to reinforce the connection with L-shaped steel plates which are pushed up to the deck plate by a small hydraulic jack. An effect of the method has been confirmed through fatigue tests.