The purpose of this article is to examine the complexity of gender discourses within children's play, analyzing preschool children's "family" pretend play. Formerly I suggested that children actively participate in their own gender identity formation, against the assumptions of "internalization" and "gender dichotomy". In this paper, I examine the dynamics of gender practices to find the complexities and pluralities of the gender discourses in preschool children's "family" pretend play. Observations were conducted at a kindergarten in Chugoku district. Research observations with kindergarten children were conducted from September 2005 to March 2006, with note-taking and digital video recording. During six days (5 hour and 12 minutes free play time), 5 "family" pretend play episodes (1 hour and 53 minutes) could be intensively observed and recorded. In each episode transcriptions were made and interpretational analysis was conducted. The findings were as follows. Firstly, children's typical "family" members are a mother, an elder daughter, a baby (girl or boy) and a cat or a dog, occasionally a father or sons joined. Secondly, the mother usually takes care of her family members, so she has power in the family. Thirdly, the detailed analysis of one episode demonstrates that there are several gender discourses related to the episode: the mother's care and the heroes' fight. Fourthly, each member struggled for a comfortable environment in their play, according to their gender. These findings were assessed in terms of the children's performativity and agency, their gender identity formation, and their play as "power play".