This study aimed to understand the current scenario of voluntary vaccination and the factors influencing its coverage among 18-month-old children of Takatsuki City, Japan. Based on 1167 parents responses, we found that voluntary vaccination coverage rates were low when compared with routine vaccination rates. The children who were not the first born of the family and who had young and poorly educated parents were less likely to receive voluntary vaccination. Japanese government-supported vaccines, such as Haemophilus influenzae type b and pneumococcal vaccine, had a higher coverage than the vaccines for which parents had to bear the entire vaccination cost. Furthermore, it was found that mass communication media and family pediatricians were effective means to disseminate voluntary vaccination-related information. We envisage that an active participation of medical professionals, easy access to vaccinations, and mass awareness programs will increase voluntary vaccination coverage in Takatsuki.