
GETTY IMAGES Image caption,Chinese J-16 fighter jets (as seen in this archive photo doing an aerobatic manoeuvre) were involved in the incursions, Taiwan said
The defence ministry said the planes entered the area in two waves, during the day and during the evening.
It comes after 38 planes, including nuclear-capable bombers, entered the zone on Friday.
China sees democratic Taiwan as a breakaway province, but Taiwan sees itself as a sovereign state.
Taiwan has been complaining for more than a year about repeated missions by China’s air force near the island.
“China has been wantonly engaged in military aggression, damaging regional peace,” Taiwan Premier Su Tseng-chang told reporters on Saturday.
But it has previously said such flights were to protect its sovereignty and also targeted “collusion” between Taiwan and the US.
- EXPLAINER: What’s behind the China-Taiwan divide?
Taiwan’s defence ministry said 20 Chinese aircraft came during the day on Saturday with a further 19 entering the area during the evening.
An air defence identification zone is an area outside of a country’s territory and national airspace – but where foreign aircraft are still identified, monitored, and controlled in the interest of national security.
It is self-declared and technically remains international airspace.
Taiwan responded by scrambling its jets and deploying missile systems.

The ministry said the Chinese aircraft included four H-6 bombers, which can carry nuclear weapons, as well as an anti-submarine aircraft.
Beijing often launches such missions to express displeasure at comments made by Taiwan.

China and Taiwan: The basics
- Why do China and Taiwan have poor relations? China and Taiwan were divided during a civil war in the 1940s, but Beijing insists the island will be reclaimed at some point, by force if necessary
- How is Taiwan governed? The island has its own constitution, democratically elected leaders, and about 300,000 active troops in its armed forces
- Who recognises Taiwan? Only a few countries recognise Taiwan. Most recognise the Chinese government in Beijing instead. The US has no official ties with Taiwan but does have a law which requires it to provide the island with the means to defend itself.