This invention implements a work system high in flexibility and speedy system development. The work system includes a plurality of modules each having software for work which performs predetermined in-module processing, and a service base unit which inputs and outputs event information to and from the modules. The event information includes an identifier and a payload. The service base unit has a function of receiving the event information from any of the modules, and a function of transferring the event information to the other module. The other module to which the event information is transferred determines based on the identifier included in the transferred event information whether the in-module processing is performed within its own module.