Delusional misidentification, a rare syndrome in which a patient displays persistent delusional misidentification of individuals or objects, occurs in several types of dementia. However, the pathology of delusional misidentification is still unclear, and there was no data pertaining to striate-frontal projection. Here, we report a case of delusional misidentification following frontotemporal dementia in which complex striate-frontal and some specific frontal gyrus dysfunction were observed. In our presented case, delusional misidentification progressed following frontal atrophy. Believing that her actual daughter had been replaced by her niece, her symptoms of delusional misidentification and frontal atrophy progressed in the short term, and social arrangement was necessary three months after the onset. There were no abnormal neurological findings including parkinsonism and general cognitive function test scores were preserved. Validated by dopamine transporter single-photon emission computed tomography, right unilateral striatal uptake decreased significantly without parkinsonism or Parkinson's disease. In addition, of specific concern, functional magnetic resonance images showed left opercular inferior frontal gyrus and right superior frontal gyrus dysfunctions. Our case study highlights complex striate-frontal projection and specific frontal gyrus dysfunctions associated with the pathology of delusional misidentification syndrome.