Abstract
Toshisada ENDO, states that the first discovery of cycloid during the Bunsei period (1818〜1828) is attributed to Nei Wada (1787～1840). On the other hand, Yoshio MIKAMI pointed out that the same subject had already been studied by Tadao SHIZUKI (1760〜1806) in his Rekishō Shinsho (vol.1,1798; Vol.2, 1800; Vol.3, 1802).
But these works seems to be insufficient, so we have discussed the same subject from astronomical points of view.
