To avoid interruption of online operation through execution of updating by way of an update system and method.

For the update system and method to be applied to computer terminal equipment enabling online operation via a network, the computer terminal equipment has a storage module, register processing module, and central processing module, while the update system has at least a detecting module and loading module. The update method detects whether a subprogram is stored in the register processing module of the computer terminal equipment, loads the update data into the register processing module, if it detects that it has not been stored, further detects whether the subprogram is executed if it detects that it has been stored, and loads the update data into the register processing module, if the detected result is that the subprogram is not executed and the update data either.