A method of producing a microfluidic device, said method comprising: a step of forming a resin layer on a support from a photosensitive resin composition that comprises a compound having at least two radical-polymerizable groups, a photoradical generator, a compound having at least two cationically reactive groups, a photocation generator, and at least one compound selected from a protective group-containing amine, a photodegradable base, an imide structure-containing compound, an amide structure-containing compound and an urea structure-containing compound, wherein the content ratio of the radical-polymerizable compound is 1 to 60% by mass and the ratio of the cationically reactive compound contained in the composition is 1 to 60% by mass, with respect to 100 % by mass of the solids contained in the composition, wherein the content of the photoradical generator in the composition is 0.1 to 40 parts by mass with respect to 100 parts by mass of the radical-polymerizable compound, wherein, in the composition, the content of the photocation generator is 0.1 to 40 parts by mass with respect to 100 parts by mass of the cationically reactive compound, wherein the content of the protective group-containing amines is 1 to 50 parts by mass with respect to 100 party by mass of the photocation generator; a step of partially UV-exposing said resin layer so that the exposure light is blocked for those parts corresponding to flow channels, to allow cross-linking of the radical-polymerizable compound to progress with radicals generated by the photoradical generator, and developing said resin layer in order to remove non-exposed parts; a step of preparing a laminate by placing a cover material on the thus developed resin layer; and a step of UV-exposing the thus obtained laminate, to allow cross-linking of the cationically reactive compound to progress with cations generated by the photocation generator. a step of forming a resin layer on a support from a photosensitive resin composition that comprises a compound having at least two radical-polymerizable groups, a photoradical generator, a compound having at least two cationically reactive groups, a photocation generator, and at least one compound selected from a protective group-containing amine, a photodegradable base, an imide structure-containing compound, an amide structure-containing compound and an urea structure-containing compound, wherein the content ratio of the radical-polymerizable compound is 1 to 60% by mass and the ratio of the cationically reactive compound contained in the composition is 1 to 60% by mass, with respect to 100 % by mass of the solids contained in the composition, wherein the content of the photoradical generator in the composition is 0.1 to 40 parts by mass with respect to 100 parts by mass of the radical-polymerizable compound, wherein, in the composition, the content of the photocation generator is 0.1 to 40 parts by mass with respect to 100 parts by mass of the cationically reactive compound, wherein the content of the protective group-containing amines is 1 to 50 parts by mass with respect to 100 party by mass of the photocation generator; a step of partially UV-exposing said resin layer so that the exposure light is blocked for those parts corresponding to flow channels, to allow cross-linking of the radical-polymerizable compound to progress with radicals generated by the photoradical generator, and developing said resin layer in order to remove non-exposed parts; a step of preparing a laminate by placing a cover material on the thus developed resin layer; and a step of UV-exposing the thus obtained laminate, to allow cross-linking of the cationically reactive compound to progress with cations generated by the photocation generator.