Objectives: The purpose of this study is to clarify whether the explanation received from the guardian at the time of inoculation of a HPV vaccine is related to preventive behaviors against uterine cervical cancer among junior high school girls. The preventive behaviors were set as “wishing to receive the HPV vaccination” and “considering on sexual behaviors (dating, kissing, sexual relations).” Methods: An anonymous self-administered questionnaire survey was performed on 206 second-year junior high school girls who were candidates for the inoculation of the HPV vaccine in the previous year. We considered that a subject received an explanation on HPV vaccination if she received explanations on this topic, such as “an HPV vaccine prevents uterine cancer.” We considered that a subject received an explanation on pubertal events if she received explanations on this topic, such as “the importance of a life.” Including these two variables among the independent variables, multiple logistic regression analysis was performed. Results: The knowledge on uterine cancer was promoted when the subjects received explanations about the HPV vaccination. Many subjects received explanations on pubertal events by receiving explanations on HPV vaccination. The guardian’s explanation about HPV vaccination was one of the factors related to “wishing to receive the HPV vaccination” and “considering on sexual behaviors.” Conclusion: It is important for guardians to explain to their children about HPV vaccination without hesitation at the time of the vaccination.