The purpose of this study was to reveal the role of friendship motivation in early stages of friendship. We examined the relationships between friendship motivation and affiliation tendencies and affect in dyadic interactions with unacquainted partners. Thirty-eight university students participated in the study. The participants were paired with a same-sex unacquainted partner and were observed in a dyadic interaction situation. The indices of affiliation tendencies were looking, smiling, and willingness to engage in future interaction with partners. The results showed that autonomous motivation was positively related to looking and willingness to engage in future interaction. Controlled motivation was positively related to negative affect before interaction. The effect of autonomous motivation on friendship formation is discussed.