PROBLEM TO BE SOLVED: To provide a manufacturing method of a resin cured product employing exposure development conditions, which is particularly suitable for a technology to cure a radical polymerization type photosensitive resin composition by exposure, a solid state imaging element using the same, and a manufacturing method of a liquid crystal display device.SOLUTION: There is provided a manufacturing method of a resin cured product, which is a method of forming a patterned resin cured product by irradiating a radical polymerization type photosensitive resin composition with exposure energy, and subsequently developing an exposed part, in which the irradiation of the exposure energy is performed to obtain a pattern having a width of 5 μm or less under the atmosphere of an oxygen density exceeding 21 volume%.
