Although moderate-to-vigorous physical activity (MVPA) has multiple health benefits, current participation in recommended MVPA level and its determinants among Japanese children and adolescents remain unclear. Therefore, this cross-sectional study investigated the prevalence of meeting recommended MVPA level and its correlates among Japanese children and adolescents.Using the Japanese version of the World Health Organization (WHO) Health Behaviour in School-aged Children survey questionnaire, we confirmed the prevalence of meeting recommended MVPA level in all primary schools (PS) and junior high schools (JHS) in Unnan City, Japan. We evaluated its association with school grade, gender, body weight status, screen time, consumption of breakfast, PA preference, and population density by using Poisson regression.We found that 20.1% of the 1,794 students (9-15 years old) met the WHO recommendation. Meeting recommended MVPA level was significantly associated with being in the sixth grade of PS (prevalence ratio (PR) = 0.57; 95% confidence interval (CI), 0.39-0.84) and first (PR = 1.52; 95% CI, 1.16-1.99), second (PR = 1.45; 95% CI, 1.10-1.90), and third grade of JHS (PR = 0.40; 95% CI, 0.26-0.62) (vs. fourth grade of PS); being a boy (PR = 1.33; 95% CI, 1.12-1.59) (vs. girl); liking PA (PR = 3.72; 95% CI, 2.22-6.22) (vs. dislike); and belonging to a medium-population-density (PR = 0.73; 95% CI, 0.61-0.88) or low-population-density area (PR = 0.67; 95% CI, 0.48-0.94) (vs. high-population-density area).About 20% of Japanese children and adolescents engaged in recommended MVPA level. MVPA was associated with grade, gender, preference for PA, and population density.