The purpose of this study is to examine the effects of therapeutic relationship as perceived by the play therapists and childhood aggression on countertransference feeling, countertransference behavior, and countertransference management ability of the play therapists. Participants were each 107 elementary students, from first grade to sixth and their play therapists. Data were analysed with SPSS 21.0. The results were as follows: First, the therapeutic relationship play therapist perceived and elementary students aggression have a influence in the play therapists’ countertranference feeling. Second, the therapeutic relationship play therapist perceived and elementary students aggression have a influence in the play therapists’ countertranference behavior. Third, the therapeutic relationship play therapist perceived has a influence in the play therapists’ countertranference management ability, while elementary students aggression has no influence. The limits and the implication of this study were included.