Digital assay method, and digital assay kit

A digital assay method for determining a concentration of a substance in a solution, comprising the steps of:

• (1) providing a substrate having a chamber array region in which 10,000 to 10 billion chambers having a volume of 1 attoliter to 100 femtoliters are arranged, wherein the substrate has light permeability and the chambers recess from a surface of the substrate,
• (2) introducing a solution containing a substance onto the chamber array region of the substrate,
• (3) covering the chamber array region of the substrate with an adhesive tape comprising a base layer and an adhesive layer, followed by pressure-bonding the adhesive layer of the adhesive tape on the surface of the substrate, thereby discharging excess of the solution in the chamber array region outside the chamber array region and sealing each of the chambers containing the solution liquid-tight to function as reactors,
• (4) detecting the presence or absence of the substance in each of the reactors based on fluorescence emitted from a fluorescent substance resulting from the presence of the substance, and
• (5) determining the concentration of the substance in the solution based on the number of reactors in which the presence of the substance is detected.