A swing practice device for emitting light at impact through self-generation enables an impact moment to be checked with the naked eyes without needing a battery by emitting light at an impact time point through self-generation during swinging by using a golf club, a baseball bat, and the like. The swing practice device includes a power generation magnet provided to a shaft so as to slide in the longitudinal direction of the shaft during swinging; a power generation coil provided on the circumference of a section in which the power generation magnet moves; a light-emitting lamp connected to the power generation coil so as to be turned on by the movement of the power generation magnet; and a magnet control means for preventing the movement of the power generation magnet at a set swing speed or lower.