To provide a method of manufacturing a microchip capable of performing the surface hydrophylizing treatment of a flow channel forming part without producing roughness or cracks on the surface of a substrate comprising polydimethylsiloxane using ultraviolet rays with a specific wavelength and capable of certainly laminating two substrates to certainly manufacture an object having expected capacity.

In the method of manufacturing the microchip having a flow channel through which a medium flows by irradiating one substrate comprising polydimethylsilicon and another substrate comprising glass or polydimethylsilicon with ultraviolet rays containing light with a wavelength of 172 nm to laminate both substrates, the flow channel forming part in the surface of the substrate and the adhesive surface forming part other than the flow channel forming part are respectively irradiated with ultraviolet rays in mutually different irradiation energy quantities in an ultraviolet irradiation process.