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Background/Aim Phthalates; chemicals used in consumer products have a potential endocrine disrupting effects. Thus, certain phthalates have been regulated in products such as children’s toys in Japan since 2010. However, humans particularly vulnerable children are still exposed to phthalates. Thus, in this study the first time in Japan, we investigated consequent phthalate exposure trends in children. Methods From participants of an on-going Hokkaido birth cohort study, 300 (50 per year) were randomly selected from 2012-2017 for this study. Urine samples of 7 years old children were collected and measured 10 phthalate metabolites concentration using UPLC-MS/MS. For the trend analysis, we combined 2 consecutive year metabolite concentrations as one year. Thus samples were considered as “year 1” for 2012 and 2013, “year 2” for 2014 and 2015 and “year 3” for 2016 and 2017. Results and discussion Metabolites MnBP, MEOHP, MEHHP, and MECPP were detected in all children. A decreased creatinine adjusted median level of MnBP was observed (45.1, 38.7 and 33.0 µg/g cr) from year 1-3, respectively. In contrast, MiBP showed a slight increased median from 13.7 µg/g cr in year 1 to 14.7 µg/g cr in year 3. While MBzP declined from 2.4 to 1.6 µg/g cr in the study period. Median concentrations of DEHP metabolites; MEHP (4.8 vs 3.8), MEOHP (24.0 vs 21.1), MEHHP (30.7 vs 27.4), and MECPP (41.7 vs 37.8) showed a decreased level compared year 1 vs year 3. DiNP metabolites; MiNP (0.6 vs 0.5), OH-MiNP (3.1 vs 2.4), and cx-MiNP (10.2 vs 5.5) showed a decline median concentration as the DEHP metabolites. Conclusions Our findings revealed that except MiBP all measured phthalate metabolites show a decreased level in Japanese children urine from 2012-2017. Future studies are necessary to assess the potential health risks of phthalates and new alternative plasticizers.