This study investigates public opinion in Japan regarding space development. Manned space development (MSD) is costly and dangerous, so some feel that the Japanese government should allocate larger budgets for unmanned space development (USD), on the basis that USD has potential for more scientific results at lower cost. However, previous studies lack an empirical assessment of public opinion on which type of space development the public would prefer. We collected data through an Internet survey conducted in 2014. We randomly sampled 700 respondents from survey monitors with ratios approximating the Japanese population stratified by sex, age, and education. Questionnaire items were related to respondents' perception of space development, opinions on the continuation of MSD after fatal accidents, and opinions on which type of space development are preferable. Our results indicate a general image of MSD as being risky, unprofitable, and not promising, while UMD is viewed as being safer. Most respondents felt that the Japanese government should continue MSD even after a fatal accident once the cause of the accident has been investigated. More respondents preferred MSD over USD, but generally approved of higher government budgets for USD. These results suggest a general preference for MSD in spite of its risks and low productivity, and a preference for larger budgets being allocated to USD because of its productivity.