We studied the efficiency of service quality of loan consultants contracted to a bank in Korea. Since the consultant is not an employee of the bank, he/she is paid solely in proportion to how much he/she sell loans. In this study, a consultant is considered as a decision making unit (DMU) in the DEA (Data Envelopment Analysis) model. We use a principal component analysis-data envelopment analysis (PCADEA) model to evaluate quality efficiency of the consultants. In the first stage, we use PCA to obtain 6 synthetic indicators, including 4 input indicators and 2 output indicators, from survey results in which questionnaire items are constructed on the basis of SERVQUAL model. In the second stage, 3 DEA models allowing negative values are used to calculate the relative efficiency of each DMU. An example illustrates the proposed process of evaluating the relative quality efficiency of the loan consultants.