This invention provides a process for producing a polyimide optical waveguide, which comprises the steps of: (a) forming an undercladding layer on a substrate, (b) forming a photosensitive polyimide resin precursor composition layer on the undercladding layer, (c) irradiating the photosensitive polyimide resin precursor composition layer, excepting a region corresponding to a core pattern, with a UV light through a mask, followed by heating after exposure, (d) removing a UV-unexposed area of the layer by development, (e) heating a UV-exposed area of the layer to imidize the UV-exposed area, thereby forming a cladding layer having a desired pattern, (f) coating the region corresponding to the core pattern and a surface of the cladding layer with a polyamic acid that forms a polyimide resin having a higher refraction index than the polyimide resin of the cladding layer, and imidizing the polyamic acid by heating to form a core layer, and (g) forming an overcladding layer on the core layer, wherein the photosensitive polyimide resin precursor composition comprises: (i) a polyamic acid obtained from a tetracarboxylic dianhydride and a diamine; and (ii) a photosensitive agent comprising a specific 1,4-dihydropyridine derivative.