This study examined the factor structure of sibling relationships in Japanese female university students. Two hundred and fifteen Japanese female university students participated in this study. The Adult Sibling Relationship Scale (ASRQ, Stocker et al., 1997) was used to measure sibling relationship cognition. The model was constructed as a result of confirmatory factor analysis. "Acceptance," "Admiration," "Emotional Support," "Intimacy," "Instrumental Support," "Knowledge," "Similarity," "Antagonism," and "Maternal Rivalry" emerged as first order factors. Seven factors, namely, "Acceptance," "Admiration," "Emotional Support," "Intimacy," "Instrumental Support," "Knowledge," and "Similarity" converged into "Warmth" as a second order factor. The fit indexes of the model were adequate (RMSEA = 0.075, CFI = 0.906 = IFI = 0.907, AIC = 12686.57).