Maximum implementation capacity of commercial fusion reactors based on breeding and supply of tritium has been investigated. The implementation capacity of fusion power reactors depends upon the net tritium breeding gain and a requirement of the initial supply of tritium for a steady commercial operation. In the reference case, the maximum implementation capacity is 7 GWe in 10 years after the year of fusion introduction, 118 GWe in 20 years and 488 GWe in 25 years. It is mainly limited by the industrial construction capacity after 25 years. The maximum implementation capacity is largely depends on the preparation interval of operation as well as the tritium breeding performance. It means that subsequent reactors must start operation as soon as possible not to leave produced tritium. The requirement to the tritium breeding for a satisfactory implementation of fusion power plants is also discussed. In the case that fusion implementation is similar to the increase of fission reactors in last 40 years, tritium breeding ratio of 1.08 will be required for the early plants. On the other hand, tritium breeding ratio of 1.02 is sufficient when fusion plants are widely deployed.