The generic feature of the fast reconnection process that develops self-consistently with the growth of anomalous resistivity is numerically studied. The anomalous resistivity due to current-driven instability is quite favorable to the occurrence of the fast reconnection mechanism, and vice-versa, which leads to rapid magnetic energy conversion. As the growth of the anomalous resistivity becomes saturated, a magnetic island is suddenly formed and is attached to slow shocks standing in the extended region. In this respect, the author argues that Petschek's configuration (1964) involving a large-scale X-type magnetic field is unstable against resistive tearing mode in high-temperature plasmas where the anomalous resistivity is most effective in providing an electrical resistivity.