A three-dimensional imaging device comprising: a first imaging unit including a first imaging optical system including a first focus lens, the first imaging unit including a first imaging sensor configured to perform photoelectric conversion on subject light imaged thereon through the first imaging optical system to output a first viewpoint image; a second imaging unit including a second imaging optical system including a second focus lens, the second imaging unit including a second imaging sensor configured to perform photoelectric conversion on subject light imaged thereon through the second imaging optical system to output a second viewpoint image; a storage; a focus adjustment unit (100, 121, 104A, 104B) configured to allow the first focus lens to perform search operation within a predetermined first search range, search for a first lens position at which the subject is focused on based on the first viewpoint image acquired from the first imaging unit, and move the first focus lens to the first lens position, the focus adjustment unit configured to allow, as to the second imaging optical system, the second focus lens to perform search operation within a second search range which is narrower than the first search range and is in the vicinity of a lens position of the second focus lens corresponding to the searched first lens position, search for a second lens position at which the subject is focused on based on the second viewpoint image acquired from the second imaging unit, and move the second focus lens to the second lens position, wherein characterized in that said storage is configured to preliminarily store a focus position displacement amount between a first lens position of the first focus lens and a second lens position of the second focus lens in focusing on a subject at the same distance; and when an in-focus position of the first lens position is not found within the first search range, the focus adjustment unit is configured to allow the second focus lens to perform search operation within the first search range, search for the second lens position at which the subject is focused on based on the second viewpoint image acquired from the second imaging unit, move the second focus lens to the second lens position, calculate the first lens position based on the searched second lens position and the focus position displacement amount stored in the storage, and move the first focus lens to the first lens position. a first imaging unit including a first imaging optical system including a first focus lens, the first imaging unit including a first imaging sensor configured to perform photoelectric conversion on subject light imaged thereon through the first imaging optical system to output a first viewpoint image; a second imaging unit including a second imaging optical system including a second focus lens, the second imaging unit including a second imaging sensor configured to perform photoelectric conversion on subject light imaged thereon through the second imaging optical system to output a second viewpoint image; a storage; a focus adjustment unit (100, 121, 104A, 104B) configured to allow the first focus lens to perform search operation within a predetermined first search range, search for a first lens position at which the subject is focused on based on the first viewpoint image acquired from the first imaging unit, and move the first focus lens to the first lens position, the focus adjustment unit configured to allow, as to the second imaging optical system, the second focus lens to perform search operation within a second search range which is narrower than the first search range and is in the vicinity of a lens position of the second focus lens corresponding to the searched first lens position, search for a second lens position at which the subject is focused on based on the second viewpoint image acquired from the second imaging unit, and move the second focus lens to the second lens position, wherein characterized in that said storage is configured to preliminarily store a focus position displacement amount between a first lens position of the first focus lens and a second lens position of the second focus lens in focusing on a subject at the same distance; and when an in-focus position of the first lens position is not found within the first search range, the focus adjustment unit is configured to allow the second focus lens to perform search operation within the first search range, search for the second lens position at which the subject is focused on based on the second viewpoint image acquired from the second imaging unit, move the second focus lens to the second lens position, calculate the first lens position based on the searched second lens position and the focus position displacement amount stored in the storage, and move the first focus lens to the first lens position.