An apparatus for measuring a concentration of CO2 for a vehicle may include an indoor panel of a vehicle in which an air inlet is mounted, and a CO2 sensing unit mounted in the indoor panel, including a light emitting unit, a light receiving unit, and a case surrounding the light emitting unit and the light receiving unit so as to reflect and move light on a plane, and vertically introduced with air introduced into the inlet with respect to the plane on which light moves.