The study examines illegal insider trading between 2006 and 2014 in Taiwan and explores whether corporate governance and audit quality influence illegal insider trading activity. The empirical result indicates that illegal profit has significantly positive relation with family firms and significantly negative relation with incentive compensation for outside director. Further, the empirical result indicates that illegal insider trading has significantly positive relation with restatements and significantly negative relation with outside director and institutional ownership. However, the study shows that illegal insider trading has insignificant relation with CPA firm’s reputation, industry specialism and unqualified opinion.