For a distributed and transparent debugging environment, a controller and an executor, each which accepts operations from a user, are disposed on each of plural computers. The controller and the executor each has a setting-status manager for managing the setting of a debugger and an execution-status manager for managing the execution status of a debugger. In response to a status change, the controller and the executor each notifies other computers of the content of the change via the network. A process manager manages a debug object program according to the content of setting and sets an operation status change due to detection of a break point to an execution-status manager. Meanwhile, the process manager changes its operation in response to a change in execution status sent from another computer.