It is necessary to add PEI to the LAMP reaction solution after the LAMP reaction takes place since PEI strongly inhibits the LAMP reaction. However, opening the reaction tube after amplification is generally avoided to prevent carry-over contamination. Therefore, development of a technique for adding PEI in a closed system is needed to put this method to practical use. Some possible solutions could be to apply PEI to the lid of the reaction tube beforehand and turn the reaction tube upside down after LAMP amplification or use wax that responds to heat. Furthermore, we should be able to use technology like micro-Total Analysis system or Lab-on-a-Chip, for which much research is being conducted in recent years, to solve this problem.