This action research has a purpose to study the personality of students at the Industrial Engineering Department Faculty of Technical Education Rajamangkala University of Technology Phranakhon. By using the Peter Lauster personality test this research compares the students personality before and after taking suggestion test on personal development. The subject of test consists of 13 students selected purposive selection from students at the first group of B.S. Technical Education (5-year curriculum) on Industrial Engineering Major. The collecting-data instruments are the Peter Lauters objective test namely the self report inventory and the authors questionnaires with check-list method. The data are analyzed by using the percentage and arithmetic mean. The research results are listed as the following: 1. The studentspersonalities before taking suggestion test on personal development in middle and low level are approximaicly 62.44 (largest group) and 6.88 percent respectively totaling approximately 69.32 percent. 2. The result from the personality test : the rather low and low level of self confident measurement are totally 76.91 percent. 3. After taking the suggestion test on personal development the good level is approximately 57.85 percent increasing about 27.18 percent relative to the same level before taking the suggestion test. On the other hand the low level is approximately 0.43 percent decreaing about 94.47 pecent relative to the same level before taking the suggestion test. 4. The findings from the interview and observation show that after taking suggestion test on personal development the most students not only improve their overall personalities but also build their self-confident as well as increase their well-adkist personalties resulting in the enhancement of their self-esteem.