A 3D image capturing device includes a first light incident hole, a second light incident hole, a photosensitive element, and a processing unit. The photosensitive element is located at an intersection point between a first light path formed by the first light incident hole and a second light path formed by the second light incident hole. The processing unit includes a 3D image sensing module and a 3D image synthesizing module. The 3D image sensing module enables the photosensitive element to alternately sense at least one first image and at least one second image. The first image is sensed by the photosensitive element through the first light path and the second image is sensed by the photosensitive element through the second light path. The 3D image synthesizing module synthesizes alternate first image and second image to generate at least one 3D image.