A storage unit (100) has a storage box (110) and a base frame (130) which is removably mounted to the storage box. A hinge (160) is provided to a hinge mounting section (140) of the base frame (130) and supports a lid (150) so that the lid can be opened and closed. The hinge (160) is composed of two inner arms (170) and outer arms (180). A rotation shaft of the hinge is guarded by the inner arms (170) and outer arms (180), so that objects and fingers are prevented from being caught.