To provide an information processor, a program registration/start method and a registration/start program, allowing simultaneous materialization of both elimination of dependency relation between programs started in different layers and facilitation of registration of a program.

The information processor has: a first mediation means to be started in a first layer on a framework; a second mediation means to be started in a second layer on the framework; a communication means for performing communication between the first mediation means and the second mediation means for receiving messages from first and second programs started in the first layer and the second layer; and a registration reception means for receiving registration of the second program into the second layer, and storing setting information necessary to start the second program in the second layer in a data management means. The first mediation means starts the second mediation means according to the setting information, the second mediation means starts the second program according to the setting information, and the second program operates according to the setting information.