The first observation of the nuclear resonant scattering from the 37.1-keV level of 121Sb and the 22.5-keV level of 149Sm excited by synchrotron radiation is reported. Delayed emission of fluorescent K or L X-rays following the internal conversion process is mainly used to observe this resonance. The evaluated energy of each excited level was 37.147±0.023keV for 121Sb and 22.496±0.022 keV for 149Sm. Each half-life of the excited level was evaluated to be 3.47±0.39 ns for 121Sb and 7.40±1.15ns for 149Sm. These values agree well with the reported values for each level.