The aim of this study is to clarify the role of the axon guidance molecule Draxin in the construction of brain neural circuits by DTI-MRI. MRI was performed on draxin knockout, dra(–), and normal mice both in vivo and ex vivo. The in vivo study of dra(–) revealed that the nerve fibers in the corpus callosum did not intersect with the midline. The ex vivo study of dra(–) demonstrated that the thalamocortical nerve fibers did not extend toward the cerebral neocortex through the internal capsule. We successfully evaluated the influences caused by the Draxin loss with DTI-MRI.