NOVELTY - The apparatus (10) has corrugated hose shaped bellows (110) provided with an open end i.e. inlet/outlet (112), located in housing and extended or contracted by external force. A weight (130) is located on the bellows. A permanent magnet rotor (210) located on the weight is moved according to the extension or contraction of the bellows and movement of the weight. A generator (200) converts kinetic energy of the rotor into electric energy. A set of linear guide shafts (140) is fixed to inner sides of the housing. A linear guide block (145) connected to the weight is moved along the shafts.    USE - Wave power generating apparatus for converting periodic up-and-down motion of an ocean/sea surface or back-and-forth motion of water particles caused by waves into mechanical kinetic energy and into electric energy using an energy converter.    ADVANTAGE - The apparatus is designed such that a component corresponding to a lid of a conventional wave power generating apparatus is placed on a bottom surface of a body of the apparatus, so that the weight can be placed on the component to offset atmospheric pressure and seawater pressure, a large change can be induced in internal volume of the apparatus with respect to change in wave height while pressure inside the apparatus is maintained relatively low and the change in amplitude of the rotor with respect to amplitude of the wave height can be increased, thus generating power in an efficient manner. The apparatus can float underwater since seawater pressure acts on the body of the apparatus in a vertically upward direction. The body can be easily fixed to a seabed using a rope, thus reducing installation cost of the apparatus. The housing is coupled to the bellows by a flange and includes the linear guide block and the shafts for the extension or contraction of the bellows and linear motion of the weight, so that the apparatus has a very simple internal structure. The apparatus allows flow of seawater into the housing to be completely blocked by the bellows made of waterproof material and the flange, so that internal structures inside the housing can be completely protected, thus allowing the apparatus to be easy to maintain and install. The apparatus achieves an environment-friendly new renewable energy production technology that does not require fuel consumption and does not produce pollutants. The apparatus is not directly exposed on the sea surface such that the apparatus can be protected from marine disasters e.g. high seas.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for a method for generating wave power.    DESCRIPTION OF DRAWING(S) - The drawing shows a cross-sectional view of a wave power generating apparatus.    Wave power generating apparatus (10)    Corrugated hose shaped bellows (110)    Inlet/outlet (112)    Weight (130)    Linear guide shafts (140)    Linear guide block (145)    Generator (200)    Permanent magnet rotor (210)