In this study, we used the indicator “sense of effort effectiveness” (i.e., if you work hard, you can do most things) to determine whether differences in family structure affect children's effort (i.e., time spent studying outside school). The data were from the 2020 Japanese Longitudinal Study of Children and Parents Survey Questionnaire. The following results were obtained. First, a slightly larger proportion of children from two-parent families had greater effort effectiveness than children from single-parent families. Second, growing up in a single-parent family is associated with the occurrence of reduced motivation in children's educational achievement in which the notion that effort is rewarded is not directly linked to learning. This may be because growing up in a single-parent home reduces the number of experiences in which learning is recognized and connected to the notion that effort is rewarded. In recent years, emphasis has been placed on the role of learning support programs in creating a social place for children in addition to supporting their higher education. Importantly, this emphasis functions to encourage children to have a positive outlook on society, where they are recognized for their learning and rewarded for their efforts.