Background: This work was to get information about 90 Sr contamination of the environment by using soil and moss from selected areas in Jeju Island, Korea. Materials and Methods: The activities of 90 Sr in soil and moss samples were investigated at nine locations of Jeju island, Korea. The soil samples have been collected at 4 sites of Jeju island during June to August of 2013, analyzed for vertical distribution of 90 Sr activities. The moss samples have been collected at 5 sites of Jeju island during November of 2011 to June of 2012, and analyzed for radioactive 90 Sr. Results and Discussion: The 90 Sr vertical concentrations in the investigated soil samples were 2.77 to 18.24 Bq•kg-1 in eastern part, 1.69 to 18.27 Bq•kg-1 in northern part, 3.76 to 13.46 Bq•kg-1 in the western part and 1.09 to 8.70 Bq•kg-1 in the southern part of the Mt. Halla in Jeju island, respectively. Activities of 90 Sr show the highest value at the surface soil and decrease with depth. The activity concentration measured was in the range of 79.6 to 363 Bq•kg-1-dry moss. Conclusion: This material is expected to be basis reference for survey of environmental radioactivity in Jeju Island.