We are promoting precise observation of cosmic gamma rays in the sub-GeV/GeV energy region using a large-scale nuclear emulsion telescope with high angular resolution mounted on a balloon. We have done balloon experiments in 2011, 2015 and 2018. In 2018, we succeeded in the first detection of an astronomical gamma-ray source and imaging Vela pulsar with the highest angular resolution in the world. We conduct a balloon flight in March 2023 (GRAINE2023) and observe Vela pulsar, Galactic Center region and so on. Nuclear emulsion telescope consists of converter, time stamper and attitude monitor. Converter part is a stacked structure with nuclear emulsion films, capturing electron and positron from gamma rays. Nuclear emulsion film’s high angular resolution enables precise determination of the direction of gamma rays and measurement of momentum by multiple coulomb scattering. For the next experiments, we added chemicals to nuclear emulsion films to enhance environmental resistance. We introduced facilities for mass production of nuclear emulsion films at Nagoya University and made 20 converters with 25cm times 50cm films. We made 2.5$\mathrm{m}^{2}$ aperture emulsion telescopes which is 6.5 times larger than the previous experiment. This poster reports the results of film performance evaluation tests and mass production, and the performance of flight films in GRAINE2023.