Vent device for sealed alkaline storage battery

The sealed alkaline storage battery is provided with a closing lid (80A) having a safety vent unit (60A) which closes a gas release hole (42A) in a sealing plate (40A); and a positive electrode cap (70A) which houses the safety vent unit (60A) In a compressed state between itself and the sealing plate (40A). The safety vent unit (60A) is provided with a ventage plate (62A) which closes the gas release hole (42A), and a spring (64A) which spring-loads the ventage plate (62A) towards the gas release hole (42A) and has a compressive load to length deformation ratio ≤50 N/mm.