The present disclosure relates to a system and method of alarm for a vehicle. The present disclosure describes a alarm system for a vehicle for allowing a driver to practice a defensive drive in a weather environment which is hard to recognize the situation around the vehicle. An embodiment provides a alarm system for a vehicle including a camera operable to be disposed at the vehicle so as to have a field of view exterior of the vehicle, where the camera configured to capture image data, an image processor operable to process image data captured from the camera; a plurality of sensors disposed at the vehicle for sensing at least one of a front, side, or rear so as to capture sensing data, an alarm device for alerting a driver when detecting an object located in blind spot of the rear of the vehicle, and controller including at least one of processor configured to process at least one of (i) processing result of the captured image data and (ii) sensing data captured by the plurality of sensors.