Before May, it took about one month on average to rent out an apartment. But after capital entered the rental market, they take only two weeks or less to rent out, which clearly means that some agencies have been stocking apartments.

"In the past two years, more real estate agencies that used to mainly sell properties started to focus on the leasing business, because the property trading market was weakening," Wei said.

He added that when agencies go to landlords to obtain leasing contracts, they usually offer a price that is 10 percent higher than the average.

Zhang, the chief analyst at Centaline Property, said rents will continue to increase because all the factors contributing to such rises remain.

According to China Economic Weekly, up to 13 first-and second-tier cities in China saw rent increases of more than 20 percent in the past year.

Chengdu, the capital of the southwestern province of Sichuan, ranked top with a rise of 30.98 percent on average, followed by Shenzhen, Guangdong province, with rent growth of 29.68 percent.

Rent increases in Beijing and Guangzhou, the capital of Guangdong, also surpassed 20 percent year-on-year this month.

Zhang Guodong, 32, who works for a travel agency in Beijing, said he is considering moving to a subsidiary in Hangzhou, the capital of Zhejiang province, if the company accepts his proposal.

"The soaring rent may be the final trigger that helps me to make up my mind," he said.

"I have been thinking about this for a few months. More and more white-collar workers in Beijing have moved out to the Sixth Ring Road, which is far from the city center, and it has become common practice to rent a room instead of an apartment to save money. That's not the life I want."

Zhang Guodong said he plans to go to Hangzhou to rent a place that is bigger and nearer the city center.

"I'm willing to work hard and I also want to enjoy my life," he added.

Xin Wen contributed to this story.