[Problem] Provided are a base station, a terminal station, a radio system, a radio control method and a storage medium capable of estimating with high accuracy a utilization status of a frequency band which is assigned to or of which a preferential use is permitted to another radio system.[Solution] A base station of a radio system, which estimates a utilization status of a frequency band which is assigned to or of which a preferential use is permitted to another radio system, wherein the base station comprises an estimation means which estimates a utilization status of said frequency band, on the basis of a received signal power ratio between a received signal power value of the other radio systems and a received signal power value of the own radio system, which is obtained at least one sensing apparatus.