A nucleic acid quantification method that uses a microchip for nucleic acid amplification reaction, the microchip including an inlet through which a liquid is introduced from outside, a plurality of reaction regions provided as reaction sites of a nucleic acid amplification reaction, and a channel through which the liquid introduced through the inlet is supplied into each of the reaction regions, wherein the likelihood of the nucleic acid amplification reaction varies between the reaction regions, includes: flowing a detection target nucleic acid chain-containing solution through the channel and introducing the solution into each of the reaction regions to perform a nucleic acid amplification reaction; and detecting an amplification product in each of the reaction regions to specify the reaction regions in which the nucleic acid amplification reaction occurred.