A storage device for a vehicle includes a storage section which has a space and has an engagement hole provided on the back side in a mounting direction and in which an article is put in and taken out through an opening portion, and a detachable separator which partitions the space in the storage section, is formed in a substantially L shape having two plate sections intersecting one another when viewed from the mounting direction into the storage section, has a projecting portion which protrudes toward the front in the mounting direction and is engaged with the engagement hole, and is mounted in the engagement hole at a partitioning position to divide the space into two compartments and a compartment expanding position to form a single compartment larger than either of the two compartments in the space.