Apalutamide is a novel nonsteroidal anti-androgen which acts as a competitive antagonist of the androgen receptor, and It is used in the treatment of castration resistant prostate cancer. A 73 year old man presented with skin rash on his limbs and trunk. He had a history of prostate cancer, and was enrolled in a clinical trial with using a aplautamide and bicalutamide six months ago. The rash was developed two months after the initiation of the clinical trial. Since his skin rash and pruritus got worse with time, the study was stopped and he was referred to the dermatology department. On physical examination, erythematous scaly patch was observed on the arms, legs and back. Skin punch biopsy was done on the right arm and back. The histopathological features of the specimen were consistent with the features of psoriasiform dermatitis. Topical ointments such as bethamethasone dipropionate/calcipotriol and narrow band UVB therapy were tried. His rash got improved after the treatment. Previously, some cases of drug eruption caused by anti-androgen have been reported such as acute generalized exanthematous pustulosis, and photosensitivity. However, psoriasiform eruption has not been reported before. Here in, we report an unusual case of psoriasiform eruption caused by a novel anti-androgen.