A scanning exposure apparatus according to this invention has a light source which can change the central wavelength of exposure light to undergo pulsed oscillation, and scan-exposes a substrate with slit-like exposure light while periodically changing the central wavelength in synchronism with the pulsed oscillation of the exposure light. The scanning exposure apparatus includes a controller which controls the light source so that integrated values Sws and Swl obtained by integrating the intensity of the exposure light for each wavelength in the scanning direction in a short-wavelength range and long-wavelength range, respectively, assuming a target central wavelength as a reference satisfy: |(Sws−Swl)/(Sws +Swl)|≦0.1.