An indicator device includes a light emitting element for emitting light, and a light conducting plate having a light incidence surface for conducting light from the light emitting element inside thereof and a light output surface, for a lighted indication by the light output surface. The light conducting plate has a triangular recess recessed to form with prescribed recess depths in one planer surface thereof, for light from the light emitting element to be reflected in part. The triangular recess has a recess extremity constituting a single vertex disposed in position on an optical axis of the light emitting element and nearer to the light incidence surface than other end parts thereof. The recess depths becomes shallower as the V-form recess extends from the recess extremity, allowing for an evenness of luminance of light over the light output surface formed on the light conducting plate.