The present disclosure relates to a solid-state image pickup element in order to enable inhibition of a variation in the photoelectric conversion characteristic of an organic photoelectric conversion film due to atmospheric exposure and a manufacturing method of the solid-state image pickup element, and an electronic device. The solid-state image pickup element includes: a photoelectric conversion film formed above a semiconductor substrate; and a sidewall sealing a side face of the photoelectric conversion film. The sidewall includes a re-deposited film of a film directly under the sidewall. The present disclosure is applicable to, for example, a CMOS image sensor or the like.