This case report describes a 54-year-old man with bipolar I disorder who was treated with aripiprazole (ARP) and lithium. The patient was admitted to our hospital because of aggravation of depressive symptoms, and treatment with lamotrigine (LTG) was initiated. Two weeks after admission, we discontinued administration of ARP after the appearance of a tremor. Three weeks after discontinuing ARP, the patient developed a high fever, rigidity of the arms, diarrhea, dysphagia, and diaphoresis. We suspected these symptoms were consistent with neuroleptic malignant syndrome and therefore removed the application of LTG. After 2 days, most of the patient's symptoms and blood results had improved, leading us to conclude that the LTG treatment had induced neuroleptic malignant syndrome. Thus, the purpose of this case report was to warn psychiatrists against therapy with LTG, as it may be conducive to neuroleptic malignant syndrome.