A wave power plant arranged to be placed on or in the sea or a lake in order to produce energy, comprising a fixed or floating structure and at least one floating body (1) that moves vertically relative to the floating structure and is connected to the structure via energy transmission devices (11). The floating body (1) is designed to be held in a fixed position during part of the wave induced motion of the body (1), thus to increase the recovery of energy from the waves. A method is also disclosed, in which the body (1) is held in a fixed position during part of the time it takes for a wave crest or trough to pass the body (1).