To impede the infiltration of rainwater into a house even in strong wind and rain from any direction of the left side and right side in a vertical waterproof louver.

This vertical waterproof louver is constituted by arranging a plurality of slats of approximately dog leg shaped cross section in tandem with spaces in a frame body to form ventilating voids between the mutually adjacent slats, and providing an intermediate groove member at the back part of a center bent part of each slat of approximately dog leg shaped cross section and providing an edge groove member at the indoor side edge part of each slat of approximately dog leg shaped cross section. The vertical waterproof louver is constituted by further forming a blade piece bent in approximately L-shape to a plate face toward the outdoor side from the center bent part, at the outdoor side edge of each slat of approximately dog leg shaped cross section integrally with each slat of approximately dog leg shaped cross section.