A body fluid constituents measurement device, which performs measurement
under a setting where light intensity of the light-emitting element is
suitably stabilized, is provided. The present invention is a body fluid
constituents measurement device which comprises: a light-emitting element
that emits light onto a test paper onto which body fluid is spotted, a
light receiving element which receives reflected light of the light
emitted by said light-emitting element, a temperature measurement unit
which measures the ambient temperature in the vicinity of said
light-emitting element, a determination unit which determines conditions
of light emission based on said temperature measured at said temperature
measurement unit in order to stabilize light intensity of said
light-emitting element, and a driving control unit which controls driving
of said light-emitting element based on the conditions of light emission;
and is characterized in that it starts measurement of body fluid
constituents after the light intensity of light emitted by said
light-emitting element has been stabilized.