股市所發生的重大事件會直接影響投資人的投資決策，值得深入的探究。因此，本研究針對我國近期發生的證所稅開徵事件，進行投資人投資心理與投資行為影響的探討。由證劵市場交易變異量、投資心理、投資行為、人格特質與從眾行為傾向等構面建置研究模型，以瞭解不同人格特質與從眾行為傾向投資人面對事件時，產生對投資心理與投資行為的影響。 本研究藉問卷調查蒐集樣本數據，並有良好之信度與效度。各構面間進行相關分析與迴歸分析，以檢定研究假設是否成立。統計人口變項再以變異數分析，驗證不同年齡、學歷、職業、職務、交易頻率與投資金額等對投資人在各構面所產生的認知差異。 研究結果顯示證劵市場交易變異量、人格特質與從眾行為傾向對投資心理產生影響，而投資心理亦會影響投資人的投資行為。人口統計變項的分析結論為，知識程度高者或專業投資者對自我認知的意識較為強烈，願意承擔風險，其交易頻率與金額亦可能較高；但軍公教投資者較會採取規避風險的態度。此可提供證券業發展差別服務與行銷策略之參考。 Significant events in the stock market will directly affect the investment decisions of investors, which is worthy of in-depth inquiry. Therefore this study is to investigate how securities trading income tax affects the mentality and behavior of investors. Using abnormal trading volumes, mentality of investors, behavior of investors, personality traits and herd behavior to build the research model, and to understand how trendencies of investors with different personality traits and herd behavior can affect their mentality and behavior when facing events. The research conduct surveys to collect sample data with good reliability and validity; do correlation analysis and regression analysis between each dimension; then test whether the research assumptions establish. It also use demographic variables with ANOVA to verify how different age, education, occupation, position, frequency of transactions and investment amounts cause differences of investor’s cognition in each dimension. Research results indicate abnormal trading volumes, personality traits and herd behavior tend to have an impact on mentality of investors; and mentality of investors will also affect their behavior. Additional research on analyzing demographic variables concluded that highly educated or professional investors have strong senses of self-perception and are willing to take risks, their transaction frequency and amounts may also be higher. But investors who are servicemen, civil servant and teachers are more likely to take a risk-averse approach. The result of this research provides suggestions of developing differentiated services and marketing strategy for the securities industry.