To provide a system development supporting method capable of incubating a local IT industry and promoting the local IT industry in a local municipal government.

A business plan 101 is prepared (step S301). On the basis of the prepared business plan 101, a systematization team 200 creates a systematization plan 103, specifications 104, and test specifications 105 separately (steps S302 to S304). Then, when the systematization plan 103, the specifications 104 and the test specifications 105 are completed (step S305: Yes), on the basis of the completed systematization plan 103, the specifications 104 and the test specifications 105, a system development bid processing 106, an acceptance validation test bid processing 107, and an operation bid processing 108 are performed individually (steps S306 to S308). Thus, a development lot is subdivided.