1. A method of generating a development environment for developing a system LSI, comprising: analyzing an input command; and in accordance with the analyzed command, generating a compiler customizing section, assembler customizing section, and simulator generating section on the basis of information of a configuration designation file in which a configuration of a system LSI is described, wherein the configuration designation file contains designation of hardware which executes an instruction, the compiler customizing section generates a compiler to develop the system LSI, the assembler customizing section generates an assembler, and the simulator generating section generates a simulator.