An optical device includes a center section having a lens portion for modifying distribution of a first part of light emitted by a light source, and a peripheral section surrounding the center section and including a conical surface for modifying distribution of a second part of the light emitted by the light source. The conical surface includes ridges where total internal reflection takes place when a light beam arrives from the light source at one of side surfaces of each ridge, and surface penetration takes place when the reflected light beam arrives at the other side surface of the ridge under consideration. Thus, the conical surface acts both as a reflective surface and as a refractive surface for achieving a desired light distribution pattern.