An apparatus concurrently executing designing of a mechanism and developing of embedded software. A three-dimensional-mechanism model simulates an operation of the mechanism, an embedded software developing section develops a control program to control the designing and operation of the mechanism in parallel to each other, a first interface inputs designing data from a mechanism designing section to the three-dimensional-mechanism model simulator for being dynamically reflected on the three-dimensional-mechanism model, and a second interface transfers data between the three-dimensional-mechanism model simulator and the embedded software developing section while synchronizing the simulator and the embedded software developing section with each other.