In the study of the reproduction mechanism of the fern plants, the method to carry out spore culture effectively and stability are required. However, the appropriate nutrient medium composition of the fern spore culture is not shown clearly. In this study, the composition of MS medium, agar and sucrose in different densities were examined comparatively. The most appropriate nutrient medium composition, 3/4MS : 0.7％ agar : 0％ sucrose was determined for the spore culture of apogamy fern Dryopteris erythrosora. Furthermore, it was confirmed that the nutrient medium of 3％ sucrose obstructed the prothallium formation, but promoted the increase of the undifferentiated cells. The method to culture and increase prothalliums of the hybrid spores that had low germination rate was inspected, that 3％ sucrose nutrient medium was used to culture and increase protonemas of the hybrid spores, and then, the protonemas were moved to the 0％ sucrose nutrient medium for the prothallium culture, the result was that the number of the prothalliums was increased.