We report the case of a 76-year-old man with apraxia of eyelid opening (AEO) and amyotrophic lateral sclerosis with dementia (ALS-D)/frontotemporal lobar degeneration with motor neuron disease (FTLD-MND). The initial symptom was AEO. Neurological examination revealed mainly bulbar symptoms with a neurogenic pattern on needle electromyograms of the tongue muscles and the biceps muscles. Furthermore, he developed severe dementia with frontal lobe dysfunction and progressive non-fluent aphasia. Brain magnetic resonance imaging revealed severe cerebral atrophy and leukoaraiosis in the bilateral frontal lobes and the anterior part of the bilateral temporal lobes; brain 99mTc ethyl cysteinate dimer single photon emission computed tomography (ECD SPECT) showed hypoperfusion in the same areas. The patient showed improvement in stereotyped behavior and AEO after treatment with 50 mg/day of fluvoxamine maleate (the initial dose was 25 mg/day). Because serotonin receptors are markedly reduced in the frontal and temporal cortexes of patients with FTLD, we considered that dysfunction of the serotonergic system in the frontotemporal lobe caused AEO. Considering the findings of this case along with those of previous reports, we propose that there is a relatively homogeneous development of ALS-D/FTLD-MND with AEO.