The present technology relates to a solid-state imaging device, a manufacturing method, and an electronic device, which can improve sensitivity while improving color mixing. The solid-state imaging device includes a first wall provided between a pixel and a pixel arranged two-dimensionally to isolate the pixels, in which the first wall includes at least two layers including a light shielding film of a lowermost layer and a low refractive index film of which refractive index is lower than the light shielding film. The present technology can be applied to, for example, a solid-state imaging device, an electronic device having an imaging function, and the like.