Japanese has two types of two-place motion verbs whose ‘objects’ can be marked as either accusative or oblique (accusative–oblique alternations). The accusative–goal verbs mark their objects with accusative case -o or the goal marker -ni, and the accusative–source verbs mark their objects with accusative -o or the source marker -kara. Previous studies describe systematic differences in the interpretation of the arguments of these verbs and the events they denote between the two structures. This study argues that these alternating verbs are variable behavior verbs that are linked to two distinct syntactic structures. The core evidence for this claim comes from the results of two acceptability judgment experiments with Japanese native speakers that examined: (i) selectional restrictions on the subjects of the alternating verbs and (ii) the ability of their subjects to license ‘floating’ numeral quantifiers. The results of the experiments demonstrate that the accusative–source verbs alternate between the transitive and unaccusative structures, whereas the accusative–goal verbs consistently behave like transitive verbs but assign two different structural cases to their objects. Thus, the study shows that there are multiple ways in which two-place motion verbs are mapped onto distinctive syntactic structures, whereby the core meaning of the verbs and their syntactic structures together determine their interpretation.