An apparatus and a method for detecting an event from a plurality of captured images are disclosed. An apparatus for generating an individual event rule is provided, comprising an image receiver, an image synthesis unit, an event rule acquisition unit, an individual event rule generator and a rule transmitter. The image receiver receives multiple captured images from multiple cameras. The image synthesis unit synthesizes the multiple captured images through conversion functions corresponding to coordinate systems of the multiple cameras into a main image. The event rule acquisition unit acquires an event rule for the main image. The individual event rule generator converts the event rule through the conversion functions into individual event rules corresponding respectively to the cameras. The rule transmitter transmits the individual event rules for identifying a single event.