In 1810, a Japanese Buddhist monk, Fumon Entsu (1755-1834) completed his main work, Bukkoku rekisho hen (Astronomy in the Country of Buddha), and established a system of Buddhist astronomy and geography based on the idea of the flat and motionless earth. This theory is called "Bonreki (Indian astronomy)" or "Butsureki (Buddhist astronomy)". In opposition to the modern scientific worldview, especially the idea of the spherical earth and the heliocentrism, he tried to prove the existence of the flat world system of Buddhism. In order to verify this theory, Entsu calculated the movement of the heavenly bodies and predicted astronomical phenomena. He also visually demonstrated the plausibility of his Buddhist astronomy by publishing the annual calendar and making the miniature mechanical model of the Buddhist worldview. Moreover, he propagated his theory by conducting the observation of astronomical phenomena in public, making lecture tours, and publishing his works. The people influenced by Entsu's theory through these activities constituted the school named "Bonrekisha (Bonreki group)" and developed a unique thought movement, often called Bonreki undo (Bonreki movement)". In this paper, I would mainly like to introduce the works of people in the Bonreki group, which are not popularly known, and consider the meaning of this movement in the early modern and modern Japanese intellectual history. In the history of Japanese religious and Buddhist thought, the works of Entsu and his followers have simply been interpreted as a strange reaction to the modern scientific worldview. Especially, the works of Entsu's followers are almost neglected as just a mimic of the master. This paper will focus on the works and activities of Entsu's followers. Many Buddhists and even general astronomers supported Entsu's theory in his time, and many Buddhist sects established the educational systems that lectured astronomy based on the Bonreki theory in the mid-nineteenth century. In spite of these activities, the Bonreki movement suddenly disappeared and became a totally forgotten astronomical theory in the mid-Meiji period. What was the reason why once popularly spread Buddhist astronomy suddenly disappeared and had to remain silent? Focusing on this sudden disappearance and subsequent silence of the Buddhist astronomy, I would also like to think of the historical condition for modern religious discourse in Japan. Because the silence of the Bonreki theory shows that a certain type of discourse was restricted in modern Japanese society, in which any modern discourse on religion was enunciated.