PROBLEM TO BE SOLVED: To provide a water flow power generation device capable of being easily and flexibly installed at several places such as a small river and an irrigation channel and generating sufficient electric power even with a weak water flow.SOLUTION: A water flow power generation device 1 which is installed in a channel 100 having a water flow and generates electric power using the water flow comprises: a propeller 2 which rotates by receiving the water flow flowing in the channel 100; a support member 4 which fixes the propeller 2 in water; a generator 5 which generates electric power with rotation of the propeller 2; and a frame member 6 which is installed in the channel 100 at an upstream side of the propeller 2 and concentrates the water flow into the propeller 2. The frame member 6 has an upstream opening 61 positioned at the upstream side of the channel 100, a downstream opening 62 positioned at a downstream side of the channel 100 and a wall section 7 which is positioned in the water higher
