PROBLEM TO BE SOLVED: To provide a manufacturing method of natto having stringiness and umami equal to or more than those of natto obtained under conventional conditions of fermentation temperature and fermentation time.SOLUTION: A manufacturing method of natto has a fermentation process for adding glutamic acid to a cooked soybean and fermenting the same with Bacillus natto. In the fermentation process, fermentation is conducted at a temperature of 37°C to 47°C for 5 hr. to 11 hr when the cooked soybean is ground soybean, and conducted at the temperature of 37°C to 47°C for 7 hr. to 13 hr. when the cooked soybean is whole soybean.SELECTED DRAWING: NoneCOPYRIGHT: (C)2020,JPO&INPIT【課題】従来の発酵温度及び発酵時間の条件で得られた納豆と同等以上の糸引き性及び旨味を有する納豆の製造方法を提供する。【解決手段】納豆の製造方法は、蒸煮大豆にグルタミン酸を添加し、納豆菌で発酵させる発酵工程を備える方法であり、前記発酵工程において、前記蒸煮大豆がひきわり大豆である場合、37℃以上47℃以下の温度で、5時間以上11時間以下で発酵を行い、前記蒸煮大豆が丸大豆である場合、37℃以上47℃以下の温度で、7時間以上13時間以下で発酵を行う。【選択図】なし