A wave energy converter apparatus comprising at least two members (1, 2) mutually connected by connection means (4) movable for allowing the mutual displacement of the members (1, 2) in response to the waves in the water where the apparatus is placed, the apparatus further comprising energy conversion means (6) for converting the motion of the connection means (4) into electric energy, and means for storing and/or transporting elsewhere the energy produced, the apparatus being characterized in that the members (1, 2) are non-floating, completely submerged members making the apparatus, taken asa whole, neutrally buoyant, means being provided for keeping the position of each one of said submerged members substantially at rest with respect to the surrounding water with which they are in direct contact, so that the members (1, 2) will move under the wave action substantially in the same way as an undisturbed water particle placed in the same region, the at least two submerged members (1,2) being mutually spaced by the connection means (4) so as to assume respective positions affected differently by the water motion induced by the waves.