Wave activated electric power generating system, comprising: a buoy to be floating on water waves, an electric generator secured to the buoy, a rotation transform member for rotating a rotor of the generator to cause the generator to generate electric power, a flexible and elongate motion transfer medium for rotating the rotation transform member, a weight element to be suspended underwater as held by the motion transfer medium, an underwater motion restrainer adapted and constructed to provide a resistance to its own motion underwater wherein said underwater motion restrainer is suspended under the buoy, its weight being such so as to sink underwater but being lighter than said weight element, and the underwater motion restrainer being less subject than the weight element to oscillating vertically underwater, and a guide means (80, 81) for the motion transfer medium moving up and down, wherein said motion transfer medium has an end having said weight element tied thereto, and an opposite end having said underwater motion restrainer tied thereto, characterized by a flexible wire tying said underwater motion restrainer to said weight element so that said underwater motion restrainer and said weight element may not be spaced from each other by more than a distance of a predetermined length, wherein with said buoy being undulately oscillated following an undulatory oscillation of water that creates waves, substantially no motion being created by said underwater motion restrainer under water resistance causes said weight element then to be relatively moved vertically up and down and in turn the rotor of said electric generator to be rotated for power generation, by and through the motion of said motion transfer medium. a buoy to be floating on water waves, an electric generator secured to the buoy, a rotation transform member for rotating a rotor of the generator to cause the generator to generate electric power, a flexible and elongate motion transfer medium for rotating the rotation transform member, a weight element to be suspended underwater as held by the motion transfer medium, an underwater motion restrainer adapted and constructed to provide a resistance to its own motion underwater wherein said underwater motion restrainer is suspended under the buoy, its weight being such so as to sink underwater but being lighter than said weight element, and the underwater motion restrainer being less subject than the weight element to oscillating vertically underwater, and a guide means (80, 81) for the motion transfer medium moving up and down, wherein said motion transfer medium has an end having said weight element tied thereto, and an opposite end having said underwater motion restrainer tied thereto, characterized by a flexible wire tying said underwater motion restrainer to said weight element so that said underwater motion restrainer and said weight element may not be spaced from each other by more than a distance of a predetermined length, wherein with said buoy being undulately oscillated following an undulatory oscillation of water that creates waves, substantially no motion being created by said underwater motion restrainer under water resistance causes said weight element then to be relatively moved vertically up and down and in turn the rotor of said electric generator to be rotated for power generation, by and through the motion of said motion transfer medium. wherein said motion transfer medium has an end having said weight element tied thereto, and an opposite end having said underwater motion restrainer tied thereto, characterized by a flexible wire tying said underwater motion restrainer to said weight element so that said underwater motion restrainer and said weight element may not be spaced from each other by more than a distance of a predetermined length, wherein with said buoy being undulately oscillated following an undulatory oscillation of water that creates waves, substantially no motion being created by said underwater motion restrainer under water resistance causes said weight element then to be relatively moved vertically up and down and in turn the rotor of said electric generator to be rotated for power generation, by and through the motion of said motion transfer medium.