For a long time, it has been argued that the achievement motivati1on of children in advanced countries has been decreasing. To address this phenomenon, recently, some researchers have tried to find ways to transform extrinsic motivations into intrinsic motivations. In Japanese, "Makezugirai" refers to an individual's dislike at being defeated by one's peers. It may be supposed that, although "Makezugirai" as extrinsic motivation has some negative meanings, it includes the possibility of transforming extrinsic to intrinsic motivation. Based on this point of view, the "Makezugirai" scale used in the present study was developed in order to explore the positive aspects of this concept. The questionnaire to assess "Makezugirai" was administered to 223 fifth and sixth graders in an elementary school. Factor analysis showed that the "Makezugirai" scale for children consisted of the following 4 factors: motivation for self-improvement, motivation to be dominant (dominance), motivation for applause, and bitterness at being defeated by peers (mortification). All of these factors were considered to be extrinsic motivations. The α coefficients of these factors ranged from 72 to 74, and the reliability of the scales were confirmed. Sense of interdependency, self-esteem, social comparison, feelings of hope or optimism, and gender were used as predictors of the "Makezugirai" scale. Results of hierarchical multiple regression analyses showed that self-improvement was regressed on hope or optimism; dominance was regressed on hope or optimism, social comparison, gender, and interdependency; applause was regressed on interdependency, hope or optimism, and social comparison; and mortification was regressed on social comparison and interdependency. Self-esteem did not regress on any subscales of "Makezugirai". As a whole, it was clear that there were two contradictory sides to "Makezugirai": competing with others and getting along with others. Subscales of "Makezugirai" were supposed to have an effect on peer relationships. Our peer relationships scale consisted of 6 factors: feeling easy with peers (easy), conflict in personal relations (conflict), positive connection with peers (connection), selfishness, helpful towards peers (help), and behaving like a clique (clique). Multiple regression analyses indicated that self-improvement positively predicted help, connection, and easy, and negatively predicted selfishness; dominance positively predicted connection, help, and easy; and applause positively predicted connection, easy, and help. In all cases, except for mortification, subscales of "Makezugirai" related to positive sides of peer relationships. Mortification was unrelated to peer relationships. Findings were discussed in terms of transforming extrinsic to intrinsic motivation and the positive effects of "Makezugirai" in late childhood on social adaptations, mental health, and personality development.