A solar cell manufacturing method includes a step of forming a diffusion layer including a first section and a second section on a light-receiving side of a semiconductor substrate, where the first section has a first concentration of impurities, and the second section has a second concentration of the impurities that is higher than the first concentration, a step of irradiating the diffusion layer with detection light that is reflected at a higher reflectivity on the first section than on the second section, and a step of detecting the first section that corresponds to a first reflectivity, and the second section that corresponds to a second reflectivity that is lower than the first reflectivity in the diffusion layer on the basis of a difference in reflectivity of the detection light reflected off the respective sections of the diffusion layer.