An apparatus for converting wave energy into electrical energy includes a wave power generation unit including a frame and float guides. A wave power generation float is joined to the float guides for vertical motion in response to the wave energy. The wave power generation float includes at least one wave power conversion module. The wave power conversion module includes a module case and an air sealing tube formed in the module case for generally preventing fluids from entering the module case. A power transmission cable transmits electrical energy where one end of the power transmission cable passes through the air sealing tube and is joined to the frame. A cable reel winds and unwinds the power transmission cable. A power transmission drive translates a bidirectional rotation of an input shaft into a unidirectional rotation. A generator generates electrical energy in response to the unidirectional rotation.