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 provided at respective ends of the channel in the substrate; a pair of air communication ports being in communication with the channel through the respective filters ; a thermal cycle region formed between the pair of filters 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 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 ; * connecting a nozzle of the pump to the air communication ports ; * 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 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 provided at respective ends of the channel in the substrate; a pair of air communication ports being in communication with the channel through the respective filters ; a thermal cycle region formed between the pair of filters 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 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 ; * connecting a nozzle of the pump to the air communication ports ; * 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 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 ; * connecting a nozzle of the pump to the air communication ports ; * 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 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. <EOS>