Auditor performance is one of the popular benchmarks used to enable the auditor to do a good job or vice versa. In carrying out his profession, an auditor also has professional ethics and this is done in order to gain the trust of the public and this professional ethics is a standard that has been designed which are principles that apply to certain fields. This study examines professional ethics moderating the effect of Audit Tools and Linked Archived Systems, computer self-efficacy, and professional training on auditor performance. Respondents who work in a Public Accounting Firm in Semarang, Indonesia. The sample in this study were 29 Public Accounting Firms consisting of 117 auditors. Purposive sampling methodology was used to determine the sample, while multiple regression was used to test the hypothesis. The results show that the Audit Tools and Linked Archived System (ATLAS), computer self-efficacy and professional training have positive effect on auditor performance; Professional ethics strengthens the positive effect of using Audit Tools and Linked Archived System on auditor performance. Professional ethics weakens the effect of professional training on auditor performance and auditor ethics does not moderate the effect of computer self-efficacy on auditor performance.