Study of multiple meson production at cosmic ray energy, 1013 ∼1016 eV, based on the observation by emulsion chamber is performed. It is found that the effective multiplicity of gamma rays produced by nuclear interaction increases considerably as interaction energy gets higher, and is represented as ∝(ΣEγ)0.2 ∼0.3. This result is consistent with the one obtained by the analysis of clean jets and also local nuclear interactions occurred in solid producing layers. Shower age analysis of gamma ray air family supports the increasing effective multiplicity of gamma rays. These are in reasonable agreement with the picture of two kinds of fireballs belonging to different levels-H- and SH-quanta.