An optimal technique search method that is performed in a system including an execution device that is initially set in an operation environment so as to derive and perform an operation corresponding to the environment using a neural network and an evaluation device that gives parameters as initial settings to the execution device and evaluates the content of the operation of the execution device after the operation ends, the evaluation device directing the execution device to perform the operation plural times and deriving the most effective operation from the plurality of derived operation results as an optimal technique from the execution device, the method comprising: an individual defining step of allowing the evaluation device to make initial settings from a combination of a virtual cell corresponding to a node of the neural network and a virtual molecule corresponding to a numerical expression group required for virtual cell division and transmit the initial settings to the execution device; an execution device operating step of allowing the execution device to create a virtual cell division space based on the initial settings, arrange the nodes included in the initial settings, perform a calculation process based on the numerical expression group, thereby forming a neural network by virtual cell division using a cell differentiation algorithm which increases the number of the nodes by dividing a node into two nodes continuously in initial stage, changes the parameters of the nodes and stabilizes the number of the nodes when a given number of virtual cell divisions ends, inputting input data detected by a sensor provided therein to the neural network connecting the nodes whose parameters are changed after the cell differentiation, perform new virtual cell division repeatedly until expected calculation result of fitness is obtained, thereby deriving output data when the expected calculation result is obtained, completing the neural network, operating an operation unit provided therein based on the output data, and transmitting the operation result to the evaluation device; and an individual evaluating step of allowing the evaluation device to create individual evaluation for the execution device based on the received operation result, wherein the individual defining step, the execution device operating step, and the individual evaluating step are sequentially performed plural times to derive the most effective operation from the individual evaluation results. an individual defining step of allowing the evaluation device to make initial settings from a combination of a virtual cell corresponding to a node of the neural network and a virtual molecule corresponding to a numerical expression group required for virtual cell division and transmit the initial settings to the execution device; an execution device operating step of allowing the execution device to create a virtual cell division space based on the initial settings, arrange the nodes included in the initial settings, perform a calculation process based on the numerical expression group, thereby forming a neural network by virtual cell division using a cell differentiation algorithm which increases the number of the nodes by dividing a node into two nodes continuously in initial stage, changes the parameters of the nodes and stabilizes the number of the nodes when a given number of virtual cell divisions ends, inputting input data detected by a sensor provided therein to the neural network connecting the nodes whose parameters are changed after the cell differentiation, perform new virtual cell division repeatedly until expected calculation result of fitness is obtained, thereby deriving output data when the expected calculation result is obtained, completing the neural network, operating an operation unit provided therein based on the output data, and transmitting the operation result to the evaluation device; and an individual evaluating step of allowing the evaluation device to create individual evaluation for the execution device based on the received operation result, wherein the individual defining step, the execution device operating step, and the individual evaluating step are sequentially performed plural times to derive the most effective operation from the individual evaluation results.