The Gamma-ray Transient Monitor (GTM) was selected by National Space Organization (NSPO) of Taiwan to fly on Formosat 8B, planned to launch in 2024. GTM will monitor Gamma Ray Bursts (GRBs) and transient events from other sources in the energy band from 15 keV to 2 MeV. GTM PI is Prof. Hsiang-Kuang Chang of Institute of Astronomy, NTHU. Co-PIs are Dr. Chih-Hsun Lin of Institute of Physics, Academia Sinica and Prof. Che-Chih Tsao of Department of Power Mechanical Engineering, NTHU. GTM was also selected for feasibility study to fly on board a lunar-orbit spacecraft of NSPO, planned to launch in 2025.