Chloroplast relocations have been known to be induced in response to light conditions. Chloroplasts move toward weak light and avoid from strong light. Dark-induced relocation, called dark position, has also been known. Although studies on chloroplast relocation by light have been performed since approximately 100 years ago, the studies by other stimuli have been carried out poorly. In this study, we found that low temperature induces chloroplast relocation (termed cold position) in prothalli of the fern Adiantum capillus-veneris. When prothalli were incubated at 25 degrees Celsius under weak light, chloroplasts accumulated along the periclinal cell wall. When the prothalli were subsequently incubated at 4 degrees Celsius under weak light, the chloroplasts relocated to and congregated at the anticlinal cell wall. Cold positioning was not observed in mutant ferns defective of a photoreceptor, phototropin 2. These results indicate that cold positioning is mediated by phototropin 2 under cold condition in fern.