To provide a simple hydroelectric power unit which utilizes high-speed flowing water in fields and mountains, which can be easily installed, which can obtain a desired electric-generating capacity at a low installation cost, and which enables storage of electricity according to need.

This simple hydroelectric power unit utilizing the high-speed flowing water in the fields and mountains is characterized as follows: a water wheel 2 is installed in the flowing water 1 in a fall having a drop greater than the water wheel 2 installed on a fixing base 3 with a mounting portion; power-generating equipment 6 is provided via a speed-increasing gear 7 on the rotating shaft 4 of the water wheel 2; and a voltage stabilizer 13 and a capacitor 14 are connected. The power-generating equipment 6 is connected to each of the rotating shafts 4 which are provided on both the sides of the water wheel 2. A manual clutch 8 is provided between the rotating shaft 4 of the water wheel 2 and the speed-increasing gear 7.