本文主要探討所有權特性對多角化行為的影響,並加入經理人的過度自信傾向,以檢驗經理人的態度是否對於不同所有權型態的企業在進行多角化時具有調節效果,並進一步將經理人區分為三類(非家族企業經理人、家族企業的家族CEO、家族企業的非家族CEO),以了解不同類型的經理人過度自信程度的差異及此差異對多角化行為的影響。本研究以2003年至2007年間台灣上市公司共677家為樣本,並以羅吉斯迴歸(Logit regression)分析方法及Tobit迴歸分析方法進行假說驗證。實證結果發現,相較於非家族企業,家族企業比較不會多角化;而經理人若具有過度自信傾向時,其採取多角化的程度會較高。當家族企業加入經理人的過度自信因素時,其對多角化的關係會由原先的負向顯著轉為正向顯著,即家族企業會更採取多角化,表示經理人過度自信因素在家族企業與多角化行為之間存有調節效果。 本文更深入探討經理人的任期以及教育程度對過度自信的影響,實證結果發現任期對於經理人的過度自信無顯著影響,而當經理人的教育程度愈高時,則愈有過度自信的傾向。三類經理人中,以非家族企業經理人的樂觀程度最大;而家族企業的家族CEO,採取多角化的程度會最小。 In this paper we examine the relation between family business and firm’s diversification. We also use managerial overconfidence to investigate whether the attitude of managers will cause moderator effect to family business and diversification or not. In addition, we separate managers into three groups (managers of non-family business, family managers in family business, non-family managers in family business) to understand the difference of diversification and overconfidence between these three groups. The sample contains the listed companies of TSEC from 2003 to 2007 and the data come from Taiwan Economic Journal Database. We use Logit regression and Tobit regression to examine this paper. The results indicate that compare with non-family business, family business engages in less diversification. And if managers are overconfident, they tend to have greater level of diversification. When we put overconfidence into family business, the result of diversification will change significant negative into significant positive. That means family business will engage in more diversification and the moderator effect of overconfidence really exists between family business and diversification. We further investigate the effects of manager’s tenure and education to overconfidence. We find that there is no significant effect between overconfidence and manager’s tenure. But if managers have higher education, they tend to be more overconfident. Among the three different types of managers, managers of non-family business have the greatest level of overconfidence, and family managers in family business experience least diversification.