A data processing device includes: data processing stages having a processing element, a stage memory and an event controller; and an inter-stage bus connecting the stages via an access point. External and process completion events are input into the controller for generating a task start event toward the processing element according to the external and process completion events. Each access point has an access table storing a data write history when the processing element writes data in the memory in a memory access process. The processing element executes an event access process indicative of memory access process completion after the processing element completes the memory access process to the memory via the access point. The access point executes another event access process for inputting the process completion event into the controller of another stage, based on the data write history when the processing element executes the event access process.