An actively Q-switched Er:YAG laser generating pulses at 2.94 microm has been developed and investigated. For a single Er:YAG generator at 3 Hz repetition rate, pulses of 91.2 ns duration and 137 mJ energy have been obtained. It corresponds to pulse train with high-peak power of ~ 1.5 MW. For 10 Hz repetition rate 30 mJ of output energy in single pulse has been achieved. These results, according to our knowledge, are the best world-wide achievements.