A method for generating a network to cope with a conditional part or an IF part having a comparison between variable data and a logical sum between comparisons which appear in a Rete network adopted in a production system using the knowledge technology scheme. In association with an intra-node, a candidate node is disposed in another conditional clause referencing a variable, and a data which was previously accepted but which did not satisfy the conditions or a data most likely to pass through the network is stored in the candidate node in advance. For the intra-node in the object processing, the value of the candidate node is loaded for judging the conditions.