A bicycle according to the present invention includes: a body configured such that a saddle and handlebars are disposed on a frame; a front wheel and a rear wheel disposed on the front and rear sides of the body, respectively; a pair of first driven units disposed on one side and remaining side of the rear wheel, respectively, and mounted around a rotating shaft; a pair of power generation units disposed on the one side and remaining side of the rear wheel, respectively, and mounted around the rotating shaft to be rotatable in upward and downward directions; and power transfer units disposed on the one side and remaining side of the rear wheel, respectively, connected to the first driven units and the power generation units, and configured to, when the power generation units are rotated, be rotated and transfer rotating power to the first driven units.