Mobile body control device, mobile body control method, and non-transitory computer-readable storage medium

A mobile body control device includes, an external environment detector configured to detect a peripheral mobile body, an estimated course calculator configured to calculate a first estimated course and a second estimated course, a preceding mobile body determiner configured to determine, as a preceding mobile body, the peripheral mobile body that overlaps with at least one of the first estimated course and the second estimated course, and a following controller configured to execute following control to follow the preceding mobile body. In a case where the peripheral mobile body to be determined as the preceding mobile body does not exist, the preceding mobile body determiner determines, as a preliminary preceding mobile body, the peripheral mobile body that overlaps with an intermediate area defined between the first estimated course and the second estimated course, and the following controller executes the following control to follow the preliminary preceding mobile body.