Nature restoration project by the Kamigori Junior High School Science Club（KSC）was planned and performed to conserved the endangered species of a freshwater red alga ‘Chisujinori’ （Thorea okadae ） in the Yasumuro River(Chigusa River System) through the town of Kamigori， Hyogo Prefecture. In field survey，measurements of environmental factors showed that water temperature and depth relatively increased at the site of Thorea occurrence. In field experiment, we performed two way disturbance manupilations by artificially rolling stones on river bed and brushing up the substrates, to examine the disturbance effect on abundance of gametophytes of Thorea . Our results suggested that the both manupilations caused the sporophytes（Chantransia stage） of Thorea quickly recoverd from September to October and decreased from October to January, whereas no gametophytes occured.
