Abstract: A ladder support device for a roof for holding a ladder on a roof. The ladder support device for a roof includes a first plate and a second plate. The first plate has a bottom edge, a top edge and a pair of side edges. The second plate has a bottom edge, a top edge and a pair of side edges. The top edges of the first and second plates are attached to each other along their lengths such that the plates are in an angular relationship with respect to each other. The plates have a top surface and a bottom surface. A bracket is coupled to the bottom edge of the first plate for removably engaging a top rung of the ladder. A block member is attached to the bottom surface of the first plate. The block member is positioned adjacent to and extends along the width of the second plate. The plates are placed on opposite sides of a roof to hold the ladder on the roof.