A novel standard light source with a more simplified construction, which is suitable for measurement of total luminous flux of a light source different in luminous intensity distribution characteristics from a conventional standard light source, and a measurement method with the use of that standard light source are provided. A standard light source includes a light emitting portion, a power feed portion electrically connected to the light emitting portion, and a restriction portion provided between the light emitting portion and the power feed portion, for restricting propagation of light radiated from the light emitting portion toward the power feed portion. A surface of the restriction portion on which light from the light emitting portion is incident is constructed for diffuse reflection.