This paper describes an evaluation experiment designed to determine groups of subjects who prefer reading MT outputs to reading the original text. Our approach can be applied to any language pairs, but we will explain the methodology by taking English to Japanese translation as an example. In the case of E-J MT, it can be assumed that main users are Japanese and that most of them have some knowledge of English. It is often the case, in the case of E-J MT systems, that those people who are comfortable with reading English do not find E-J MT outputs useful, and in many cases, they would rather prefer reading the original English text. On the other hand, E- J MT outputs prove to be useful to those who find it hard to read the original English texts. We have used the reading comprehension part of the Test Of English for International Communication (TOEIC) to determine the threshold English ability level, dividing these two user groups.