A power generator according to an embodiment of the present invention, as a generator which generates electricity by using fluid which flows horizontally, includes: a linear reciprocation member which is arranged in the fluid and linearly reciprocates in both directions which are perpendicular about the horizontal flow; a first conversion unit which converts a linearly reciprocating motion into a bidirectional rotary motion and delivers the bidirectional rotary motion; a second conversion unit which converts the linearly reciprocating motion into an unidirectional rotary motion and outputs the unidirectional rotary motion; and a power generation unit which generates electricity by using the unidirectional rotary motion which is outputted from the second conversion unit.
