The traditional financial theory assumes that the market is efficient, however, the real estate market is less efficient than the security market. Due to the lack of transparent information, home buyers can not react to market information rationally. They may choose to follow other peoples' decisions and lead to the herding behavior and price volatility or unusual transactions. Most previous studies employed the return and its deviation as the measurement of the herding behavior, however, the trading volume volatility is the indicator of herding behavior prior to return. This study thus intends to examine the trading volume in the residential real estate market to observe the herding behavior in Taiwan. Results show that the herding behavior of residential real estate market exists in Taipei City. In contrast, the effect on Taichung and Kaohsiung is not significant. Factors attributing to the different results may include the industry concentration, employment opportunity and the relative scarcity of housing supply in various regions. We also find that the transactions of herding behavior in the residential real estate market may be affected by user cost of housing and previous market returns. Furthermore, some macroeconomic factors (i.e., economic growth rate, construction stocks index, change of housing rents and construction costs) impose positive impact on the housing transactions. On the contrary, mortgage interest rates and consumer price index have negative influence. This paper is the first study focusing the trading volume in the real estate market for the herding behavior in Taiwan. Results may provide precious lessons for homebuyers, investors, administrative authorities, and policy makers.