In this study, Cyclophilin isolated from cDNA library for Griffithsia japonica among the red algae was named as GjCyp-1 and we investigated the function and characterization of GjCyp-1. For studying the function of the gene, a recombinant GjCyp-1 containing a CaMV35S promoter at the amino-terminus was constructed and expressed in Nicotiana tabacum. Tobacco seedlings confirmed as transgenic sense plant were heat shocked for 2 h at $45^{circ}C$ and then its chlorophyll contents were compared with the tobacco seedlings carrying only the vector under the same heat shock. The results strongly supported the protective effect of red algal Cyp against heat stress. To investigate the subcellular localization of GjCyp-1, GjCyp-1 was translationally fused in-frame to the N-terminus of soluble-modified green fluorescent protein (smGFP). In analysis of confocal microscopy using particle gun bombardment, the smGFP-fusion protein was confirmed in the cytosol of onion epidermal cells. Here, it was suggested that GjCyp-1 was a algal CypA lineage localizing in cytosol and induced thermoprotective activity.