2022-07-29 日付の足し算 python import datetime dt1 = datetime.datetime(2022, 9, 3) print(dt1) dt2 = dt1 - datetime.timedelta(days=28) print(dt2) dt2 = dt1 - datetime.timedelta(days=21) print(dt2) 2022-09-03 00:00:00 2022-08-06 00:00:00 2022-08-13 00:00:00