Taking to Twitter the defence ministry said, "21 PLA aircraft (J-11*8, J-16*10, KJ-500 AEW&C, Y-9 EW and Y-8 ELINT) entered Taiwan's southwest ADIZ on August 2, 2022."
In response, Taiwan scrambled a combat air patrol, sent radio warnings, and deployed defence missile systems to track the Chinese military planes, the MND said.
Pelosi landed in Taiwan on Tuesday as part of a Congressional delegation's tour of the Indo-Pacific region in the face of the China threat.
Minutes after her aircraft landed in Taipei, the Chinese People's Liberation Army announced that it would hold six live-fire military drills in waters around Taiwan, scheduled to take place from Thursday to Sunday.
In response to China's announcement of the drills, Taiwan's defence ministry said that China's plans to hold six live-fire military drills in waters around Taiwan over the next few days are an attempt to threaten Taiwan's major ports and metropolitan areas.
"This unilateral effort to undermine regional peace and stability will not help China's international image and will hurt the feelings of people on both sides of the Taiwan Strait," the MND said in a statement, while strongly condemning the Chinese plans, reported Focus Taiwan.
It further said that the PLA's planned drills show its mentality and how it resorts to force to resolve differences and undermine regional peace and stability.
However the ministry is closely monitoring the PLA's movements and will respond appropriately to any actions by the Chinese military, MND added.
According to Chinese media reports, China announced to carry out the drills in waters north, northeast, northwest, east, south and southwest of the nation in the Taiwan Strait, the Bashi Channel, the East China Sea and the Pacific.
It further said that one of the locations of the planned drills is less than 20 kilometres from Kaohsiung in southern Taiwan.
"The Chinese armed forces will begin military operations around Taiwan, long-range live firing will be held in the Taiwan Strait, and conventional missile tests will be organized in the sea area of the eastern part of the island," Chinese People's Liberation Army Eastern Theater Command spokesperson Shi Yi said.
"These actions are a fair deterrent to the recent major escalation of US negative actions on the Taiwan issue and a serious warning to the pro-Taiwan independence forces," Shi Yi added.
China's Ministry of National Defense Spokesman, Wu Qian said that the PLA would launch a series of military countermeasures against Pelosi's "deliberate provocation" despite Beijing's repeated warnings that visiting Taiwan would bring about "serious consequences."
Pelosi's visit was a serious violation of the Three Joint Communiques and the "one China" principle, which has seriously hurt US-China relations, he said, adding that all external intervention and separatists' attempts at Taiwanese independence shall be resolutely crushed.
Meanwhile, media reports said that US Navy has deployed four warships in the Philippine Sea east of Taiwan and the Philippines and south of Japan in what it called routine deployments.
A US Navy official said that those included the aircraft carrier USS Ronald Reagan, the guided missile cruiser USS Antietam, the destroyer USS Higgins, and the big deck amphibious ship USS Tripoli, reported Focus Taiwan.
The US House Speaker, who is second in line to the Oval Office after the US vice-president, reaffirmed her country's unwavering commitment to supporting Taiwan's democracy and said this trip in no way contradicts longstanding United States policy on the self-governed island.
"Our discussions with Taiwan leadership will focus on reaffirming our support for our partner and on promoting our shared interests, including advancing a free and open Indo-Pacific region," Pelosi said in a statement after arriving in Taiwan.
She expressed US solidarity with 23 million people of Taiwan in the face of the increasing threat from China.
China firmly opposed Pelosi's Taiwan visit and called the trip a serious violation of the one-China principle and the provisions of the joint communique signed between the two countries.
Beijing said the visit gravely undermines peace and stability across the Taiwan Strait, and sends a seriously wrong signal to the "separatist forces for Taiwan independence".