A hydroelectric power plant for converting hydrostatic water pressure into electric energy, the hydroelectric power plant comprising: - a supply water pipe - two support structures (8a, 8b) for the hydroelectric power plant - troughs moving to the same direction between the support structures (8a, 8b), the troughs being open from one side and configured to move in a closed circle essentially in vertical direction, the troughs being configured to be filled with water in a top dead centre of the vertical movement of the troughs and to be drained from water in a bottom dead centre of the vertical movement of the troughs - bearing means (23a, 23b, 23d, 24a1, 24a2) for attaching an individual trough in an articulated manner to at least two parallel chains (24a, 24b, 24c) - at least two parallel chains (24a, 24b, 24c), parallel gearwheels (25a, 25b, 25c) and rotating shafts (26a, 27a, 28a), wherein the parallel chains (24a, 24b, 24c) are installed to said parallel gearwheels (25a, 25b, 25c), which are installed in a fixed manner to said rotating shafts (26a, 27a, 28a) so that the vertical movement of the parallel chains (24a, 24b, 24c) is configured to rotate the gearwheels (25a,25b, 25c) supporting these and said rotating shafts (26a, 27a, 28a) - a first end of the rotating shafts (26a, 27a, 28a) is bearing-mounted to a first support structure of the hydroelectric power plant and a second end to a second support structure, and - a stator shaft of an electric generator is attached to at least one rotating shaft (26a, 27a, 28a), characterized in that at least at the first end of each rotating shaft (26a, 27a, 28a) there are provided load relief gearwheels (26, 27, 28), which are configured to rotate together by means of auxiliary gearwheels (29a, 29b) for reducing the load of the parallel chains (24a, 24b, 24c) moving in the vertical direction. - a supply water pipe - two support structures (8a, 8b) for the hydroelectric power plant - troughs moving to the same direction between the support structures (8a, 8b), the troughs being open from one side and configured to move in a closed circle essentially in vertical direction, the troughs being configured to be filled with water in a top dead centre of the vertical movement of the troughs and to be drained from water in a bottom dead centre of the vertical movement of the troughs - bearing means (23a, 23b, 23d, 24a1, 24a2) for attaching an individual trough in an articulated manner to at least two parallel chains (24a, 24b, 24c) - at least two parallel chains (24a, 24b, 24c), parallel gearwheels (25a, 25b, 25c) and rotating shafts (26a, 27a, 28a), wherein the parallel chains (24a, 24b, 24c) are installed to said parallel gearwheels (25a, 25b, 25c), which are installed in a fixed manner to said rotating shafts (26a, 27a, 28a) so that the vertical movement of the parallel chains (24a, 24b, 24c) is configured to rotate the gearwheels (25a,25b, 25c) supporting these and said rotating shafts (26a, 27a, 28a) - a first end of the rotating shafts (26a, 27a, 28a) is bearing-mounted to a first support structure of the hydroelectric power plant and a second end to a second support structure, and - a stator shaft of an electric generator is attached to at least one rotating shaft (26a, 27a, 28a), characterized in that at least at the first end of each rotating shaft (26a, 27a, 28a) there are provided load relief gearwheels (26, 27, 28), which are configured to rotate together by means of auxiliary gearwheels (29a, 29b) for reducing the load of the parallel chains (24a, 24b, 24c) moving in the vertical direction.