The purpose of this research was to study the characteristics of the audit committee to reduce the companys chances of receiving modified audit opinions from the audit. This study used the data from the annual reports of the companies listed on the Stock Exchange of Thailand between the year 2015 to 2018. The data used were the audit committees and modified audit opinions of 211 companies consisted of 92 industrial product companies and 119 companies in service provider category. The variable data were analyzed by using descriptive statistics and inferential statistics then the logistic regression correlation analysis Pearson correlation matrix and logistic regression analysis were used to test the hypotheses. The independent variables were audit committee characteristics consisted of the independence size number of meetings and accounting or financial expertise. The dependent variable was the modified audit opinions. The results revealed that the number of meetings of the audit committee was the only variables of the audit committee characteristics that showed a positive correlation with the modified audit opinions. There was no significant relationship between the independence of the audit committee the audit committee size the expertise in accounting or finance and the modified audit opinions. The equation of predicting the characteristics of the audit committee which is an important part of corporate governance significantly showed that it had no influence on reducing the chance that the company would receive a modified audit opinion. However the research results suggested the evidences in policy implications and operation of corporate governance in characteristics of effective audit committee. The audit committee meetings not only the numbers but also the quality of the meetings should be considered to enhance corporate governance efficacy concerning the quality of financial reports

The objectives of this research is for study of Quality Control in accordance with Quality Control Standard No.1 (TSQC1) and Audit Quality test the difference of Quality Control in accordance with Quality Control Standard No.1 (TSQC1) and Audit Quality test the relationship and positive impact of quality control of audit firm in accordance with Quality Control Standard No.1 (TSQC1) with Overview Audit Quality of Big 4 and Non-Big 4 Auditing Firms. This research is done by give out questionnaires and in-depth interviews method which used populations of 228 auditors certified by the Securities and Exchange Commission in Thailand by receiving 115 replied questionnaires which considered as 50 percent and using Descriptive Statistics T-test Statistics Pearson’s Correlation Coefficient and Stepwise Multiple Regression Analysis The results say that Quality Control in accordance with Quality Control Standard No.1 (TSQC1) in overview and individual element of Big 4 and Non-Big 4 Auditing Firms completely applied. Big 4 Auditing Firms have higher average than Non-Big 4 Auditing Firms highest average is for ethical requirement. Audit Quality both in overview and individual element Big 4 and Non-Big 4 Auditing Firms completely applied. Big 4 Auditing Firms have higher average than Non-Big 4 Auditing Firms highest average is for clearness. From test hypothesis of quality control of auditing firm in accordance with Quality Control Standard No.1 (TSQC1) of Big 4 and Non-Big 4 Auditing Firms is according to assumptions by having differences in all elements while Audit Quality is according to assumptions only one element which is clearness no difference in statistical significant. Quality Control in accordance with Quality Control Standard No.1 (TSQC1) has relationship and positive impact with Audit Quality and from prediction equation find that enhance of audit quality of auditing firm should emphasize to Quality Control in accordance with Quality Control Standard No.1 (TSQC1) in engagement performance and ethical requirement.