To reduce overhead of CSI feedback without decreasing throughput in applying CoMP transmission, a radio communication method of the invention is characterized by including, in a user terminal measuring quality information for each of cells to perform Coordinated Multi-Point transmission, and notifying a radio base station apparatus of the quality information, in the radio base station apparatus calculating a quality difference between the cells to perform Coordinated Multi-Point transmission, by using the quality information for each the cells from the user terminal, determining granularity of inter-cell channel state information for each of the cells based on the quality difference, and notifying the user terminal of the granularity, and, in that the user terminal generating inter-cell channel state information for each of the cells according to the granularity from the radio base station apparatus, and transmitting the inter-cell channel state information for each of the cells to radio base station apparatuses of cells to perform Coordinated Multi-Point transmission.