A software automatic generation process and semantics of software generated by Lyee can be formatted by using the process algebra. A software generation method includes: a first step of declaring (defining) a user requirement to be mounted as one program according to a word name, a definition equation, an execution condition of the definition equation, an I/O attribute, and a word value attribute for each logic body and for each word on the logic body; a second step of creating logic elements (L2, L3, L4) made into a module as a process cell having an I/O channel by the Lyee calculation method and function elements (I2, O4, S4) from the declaration of the word unit; a third step of collectivizing the logic elements and the function elements into a set having a set condition to cause an interaction by a command from the same screen; a fourth step of arranging one control function module Φ for each of the sets; and a fifth step of arranging one control function module Ψ for the program.