No reproducible and efficient transformation system has been developed, despite many attempts made to obtain transformed plants in tea (Camellia sinensis). This is because no efficient and stable tissue culture system for tea has been developed yet. In order to develop such a system, it is essential to analyze the materials used for tissue culture as well as tissue culture conditions. The National Research Institute of Vegetable and Tea Science in Makurazaki maintains a collection of various tea clones (var. sinensis, var. assamica) from Japan, China, India, and other Asian countries. We tested 130 strains by cotyledon culture to identify strains with a high potential for somatic embryogenesis. Cotyledons in immature seeds derived from natural crosses were used as explants. Embryos were cut out, then both cotyledons derived from each seed were placed onto solid MS medium containing 3.0 mg/L BA, 3% sucrose, and 0.2% gellan gum for somatic embryo induction. The medium was adjusted to pH 5.8 prior to autoclaving. Cotyledons were cultured in the dark at 25°C. Thirteen strains formed somatic embryos directly on the surface of the cotyledons. The Chinese strain ‘Makura-Ck2’ showed the highest frequency of somatic embryo formation, with clusters consisting of large numbers of somatic embryos.