GRBs have been recently known as a unique probe to catch the highest z galaxies and stars. Here I propose the new trigger method to catch high-z GRBs with z &gt
10 efficiently by imaging sub-MeV gamma rays from GRBs. We have developed the Electron Tracking Compton Camera (ETCC) with reconstructing tracks of the recoil electron in Compton process to explore the MeV gamma-ray astronomy. By measuring the track of a recoil electron, the direction of the incident gamma ray is determined for each photon, which enables us to reconstruct the direction of GRBs by detecting only several ten photons (&gt
100keV). Ability of the large ETCC (100cm2 effective area) to detect GRBs with z ∼ 20 is revealed, based on the results of the balloon experiment and laboratory imaging test using the small ETCC. © 2010 American Institute of Physics.