A lamp for a moving vehicle which can function as a headlamp and as a lower-brightness running lamp includes a single light emitting device, a power regulator, a first lampshade, a light guiding element, a lifting device, and a number of first reflecting covers. The first lampshade is arranged facing the light emitting device. The light guiding element gathers light from the light source and emits the light from a lower part of the moving vehicle and the power regulator can supply full power or reduced power to the light source. The lifting device holds the light guiding element and can raise it up or down so that emitted light reaches either the first lampshade or reaches first reflecting covers depending on the lighting function required.