The present disclosure provides a method for producing a microchannel device, which can form a channel that has high hydrophobicity, high solvent resistance as well, and also resistance to heat and damage, on demand with high accuracy, and produces the microchannel device at a low cost, while having high productivity. The method for producing a microchannel device includes: forming a channel pattern from a hydrophobic resin on a porous substrate by an electrophotographic method; melting the channel pattern by heat to allow the channel pattern to permeate into the porous substrate, thereby forming a channel in the inside of the porous substrate.