The purpose of this research was to study an effect of levels of learning ability and types of feedback in an electronic portfolio on learning achievement of students in electronic media production for education subject. The samples were 113 students registered in Electronic Media Production for Education Subject divided into 6 groups : 3 control groups and 3 experimental groups. The control groups received feedback type 1 (the assessment feedbacks were excellent, good, average and improving needed then scoring) while the experimental groups received feedback type 2 (the assessment feedback were similar to the type 1, with the suggestions of errors and methods of improvement). The experiment ran for 5 weeks. The instruments were the learning ability test, learning achievement test and E-portfolio management system on web. The data were analyzed by descriptive statistic, One way ANOVA and Two way ANOVA. Results indicated that there was an interaction between levels of learning ability and types of feedback on learning achievement of students in electronic media production for education subject at 0.05 level of significant. To develop an E-portfolio of the student, an instructor needs to give specific feedback to students, including scoring, specifying errors and some advice on how to improve their work. In this way, the students can use the information, which would improve their learning achievement as well. (Contains 3 figures.) [This paper was published in: Proceedings of the Ninth Distance Learning and the Internet Conference 2008, Waseda University, Tokyo, Japan, organized by the APRU, November 19-22, 2008, Pp. 31-36.]