Chinese authorities put out a statement soon after the earthquake struck, saying they were willing to provide disaster relief assistance, El.kz cites BBC.
China's east coast lies just 180km (111 miles) from Taiwan.
"The mainland is highly concerned about the situation and extends sincere sympathy to the Taiwan compatriots affected by the disaster," said Zhu Fenglian, spokesperson for the Taiwan Affairs Office of the State Council.
Chinese state media has also been widely reporting the disaster.
China and Taiwan have a tense relationship. Taiwan sees itself as a sovereign country, but Beijing sees it as a breakaway province that will eventually be part of the country, and has not ruled out the use of force to achieve this.
The tensions are constant - in the hour just before the earthquake Taiwan's defence ministry had put out a daily briefing noting that 20 Chinese military aircraft had crossed into its self-proclaimed air defence zone in the past 24 hours.