A luminous pedal structure for a bicycle is mounted on a crank of a bicycle and contains a body, an electricity generating device, a shaft, and a covering member. Each limiting column of the electricity generating device fits with each magnetic element and inserts into each connecting post, and coils fit with limiting columns and contact with magnetic elements; the transmission set has a large chainring and plural small chainrings meshing with the large chainring meshes, the holders of the covering member connect with the limiting columns, the shaft and the limiting columns are rotated by picture bearings which rotate at different speeds and axes so as to drive the large chainring and the small chainrings to rotate, such that the magnetic elements are driven to rotate the coils so as to generate an induced voltage, by which the light-emitting elements generate a forward voltage to emit lights.