PURPOSE: To enhance the waterproofness and resistance against winds by furnishing the body with a detention part to be detained with the foremost angular part of a flat plate roofing material, putting a seal material in tight attaching with the surface of the roofing material, and arranging another seal material in tight attachment with the rear surface foremost part of the next stage roofing material.

CONSTITUTION: A down ridge member 1 consisting of metal sheet processing is composed of a body 2 furnished at the foremost with a detention part 2a having a channel-shaped longitudinal section, seal materials arranged on the rear surface of the body 2 in the flow direction of the ridge K, and another seal material 4 arranged over the facial base part of the body 2 in the left-right direction of the ridge K. This ridge member 1 is placed as straddling the left and right flat plate roofing materials 10L, 10R secured along the ridge K, and the detention part 2a is detained with the foremost angular part of the roofing materials 10L, 10R and secured to the roof by driving nails (n), and the seal materials 3, 3 are put in tight attaching to the surfaces of the roofing materials 10L, 10R. Then the rear surface foremost parts of the next stage roofing materials 10L, 10R are put in tight attachment with the seal material 4, and the next stage member 1 is placed and secured to the roof. This allows preventing rainwater from intruding to the ridge K and enhance the resistance against winds through consolidation of the member 1 and material 10.