The present invention makes efficient development possible by providing a development support device that automatically establishes a network model, messages to be transmitted and received, etc. for acooperative simulation that connects a plurality of development support devices. The present invention is characterized in that: a development support device (2) generates a communication definitionfile (11) in a format that can be read and executed by a development support device (1); and development support device (1) reads the communication definition file (11) and thereby automatically establishes messages to be transmitted and received by development support device (1).