A PCR method comprising the step of: * preparing a PCR reaction vessel, said reaction vessel comprising: a substrate; a channel formed on the substrate; a pair of filters (28, 30) provided at respective ends of the channel in the substrate; a pair of air communication ports (24, 26) being in communication with the channel through the respective filters (28, 30); a thermal cycle region formed between the pair of filters (28, 30) in the channel, the thermal cycle region including a high temperature part and a medium temperature part; a branch point formed between the pair of filters (28, 30) in the channel; a branched channel whose one end is connected to the branch point; and a sample introduction port formed at the other end of the branched channel in the substrate, the method further comprising the steps of: * introducing a sample into the PCR reaction vessel via the sample introduction port; * setting the PCR reaction vessel in a PCR device provided with a pump (103, 104); * connecting a nozzle (101, 102) of the pump (103, 104) to the air communication ports (24, 26); * detecting fluorescence generated from the sample in the thermal cycle region; * moving a sample in the thermal cycle region between the high temperature part and the medium temperature part by controlling the pressure inside the channel by the pump (103, 104) based on a change in a fluorescence amount, while a sample not subjected to PCR stays in the branched channel; and detecting, by monitoring the fluorescence from the sample inside the thermal cycle region, the progress of the reaction of the sample in real-time. a substrate; a channel formed on the substrate; a pair of filters (28, 30) provided at respective ends of the channel in the substrate; a pair of air communication ports (24, 26) being in communication with the channel through the respective filters (28, 30); a thermal cycle region formed between the pair of filters (28, 30) in the channel, the thermal cycle region including a high temperature part and a medium temperature part; a branch point formed between the pair of filters (28, 30) in the channel; a branched channel whose one end is connected to the branch point; and a sample introduction port formed at the other end of the branched channel in the substrate, the method further comprising the steps of: * introducing a sample into the PCR reaction vessel via the sample introduction port; * setting the PCR reaction vessel in a PCR device provided with a pump (103, 104); * connecting a nozzle (101, 102) of the pump (103, 104) to the air communication ports (24, 26); * detecting fluorescence generated from the sample in the thermal cycle region; * moving a sample in the thermal cycle region between the high temperature part and the medium temperature part by controlling the pressure inside the channel by the pump (103, 104) based on a change in a fluorescence amount, while a sample not subjected to PCR stays in the branched channel; and * introducing a sample into the PCR reaction vessel via the sample introduction port; * setting the PCR reaction vessel in a PCR device provided with a pump (103, 104); * connecting a nozzle (101, 102) of the pump (103, 104) to the air communication ports (24, 26); * detecting fluorescence generated from the sample in the thermal cycle region; * moving a sample in the thermal cycle region between the high temperature part and the medium temperature part by controlling the pressure inside the channel by the pump (103, 104) based on a change in a fluorescence amount, while a sample not subjected to PCR stays in the branched channel; and detecting, by monitoring the fluorescence from the sample inside the thermal cycle region, the progress of the reaction of the sample in real-time.