Heterogeneous access networks in B3G networks can provide each proper network service to mobile users. Furthermore, mobile users can use not only a unique access network service, but also different hetero network services by connecting another access network. For using another access network service, mobile terminals must support hetero network system techniques. Hence, by this multiple system modes, mobile terminals are able to implement ISHO (Inter System Handover) for changing the network service. In the heterogeneous access network environment, new resource management can be adopted to control QoS management. In this paper, we propose a resource balancing management scheme by the ISHO to increase the network availability. From the numeric analysis, we compare the proposed scheme with a current scheme.