Fire extinguishing system for vehicle battery

Proposed is a fire extinguishing system for a vehicle battery. A pressure balancing element disposed on a battery pack provides a gas path between inside and outside a battery housing. A gas path portion connected to the pressure balancing element through a ventilation valve has a terminal end open to the air, allowing gas to move between the gas path and the air. A main fire detector disposed on the gas path portion detects a fire in the battery pack. A controller outputs a control signal to extinguish the fire. An extinguishing agent supply unit supplies a fire extinguishing agent to the gas path portion through the ventilation valve and the pressure balancing element in response to the control signal. A fire occurring in the battery pack is rapidly and accurately detected and immediately and effectively extinguished.