Celiac disease (CD) is an immune-mediated enteropathy and is a rare disease in Asia, including in Korea. However, the ingestion of wheat products, which can act as a precipitating factor of CD, has increased rapidly. CD is a common cause of malabsorption, but many patients can present with various atypical manifestations as first presented symptoms, including anemia, osteopenia, infertility, and neurological symptoms. Thus, making a diagnosis is challenging. We report a case of CD that mimicked amyotrophic lateral sclerosis (ALS). The patient was a sexagenary man with a history of progressive motor weakness for 2 years. He was highly suspected as having ALS. During evaluation of his neurological symptoms, esophagogastroduodenoscopy (EGD) was performed because he had experienced loose stools and weight loss for the previous 7 months. On EGD, the duodenal mucosa appeared smooth. A biopsy revealed severe lymphoplasma cell infiltration with flattened villi. His serum endomysial antibody (immunoglobulin A) titer was 1:160 (reference, <1:40). Finally, he was diagnosed as having CD, and a gluten-free diet was immediately begun. At a 4-month follow-up, his weight and the quality of his stool had improved gradually, and the neurological manifestations had not progressed.