Recently, the use of biological agent treatments for psoriasis has increased. Ixekizumab (anti-IL 17A) is a biological agent used for the treatment of moderate to severe plaque psoriasis. Although ixekizumab is generally well tolerated, various side effects may occur after the use of this medication. Herein, we present a case of oral lichen planus possibly induced by ixekizumab in a 46-year-old woman with psoriasis. Clinicians who use ixekizumab in their patients should be careful about this side effect and follow up patients in terms of mucocutaneous liken planus.