Abstract: ~(222)Ra concentration are measured using passive integrating radon monitors in the building for nu-clear and radiochemistry in Institute of High Energy Physics. The concentrations are averaged over 5-month or 6--month periods. The results are compared with the situation of home and abroad. ~(222)Rn con-centration in outdoor is 5.7 Bq·m~(-3) which is consistent with those of other districts. Range of Rn in-door is 73--184 Bq·m~(-3) which is higher than that of general buildings.