This study examined the effect of elementary, junior high, and senior high school experience activities on the students’ self- and work-understanding, to clarify the usefulness of such experiences for the students’ career development. Eighty-four university students completed a survey to measure career development indices (basic/general purpose ability, vocational identity, career resilience); experience activities in elementary, junior high, and senior high schools; and the degree of self- and work-understanding through the activities. The results showed that the degree of self- and work-understanding through the activities were generally high, which indicates that these activities succeeded as exploratory experiences. The workplace experience, which 90 % of students had experienced during junior high school, and open campus/trial lessons, which 70% of students had attended during senior high school, promoted self- and work-understanding, and these experiences were useful for students’ career choices. The results also showed that experience activities in elementary school had a positive effect on self- and work-understanding, which promoted their career development.