A vehicular lamp includes a light source; and a light guide disposed such that light emitted from the light source is incident on an end face of the light guide. The light guide emits light, guided into its interior, heading vehicle-forward from an exit face of the light guide running along the light guide's lengthwise extension. The light guide includes reflection steps formed on a surface of the light guide on a side reverse from the exit face, for reflecting light guided into the light-guide interior toward the exit face; and a plurality of diffusion flutes formed on said end face, each being arcuate in substantially horizontal cross-section through said end face, and each being of constant form in substantially perpendicular extension.