Basic concept of functional magnetic resonance imaging(fMRI) is the detection of changing magnetic field during the activation of a neural network. The change of magnetic field depends on the hemoglobin oxidation-reduction ratio which corresponds to the degree of neural activation and following blood supply. Repeated execution of certain task and subsequent fast MRI scanning represent neuronal activation of responsible foci for the task. As it has a siginificant role in functional neuroimaging, fMRI is currently applied in many filed of brain research, particularly on the evaluation of brain function and structure. fMRI is particularly useful in the clinical field of neurodegenerative disease including dementia, cerebrovascular disease, and epilepsy.