Pain inside the penis can be caused by urethral stones, penile sclerosis, prostate disorders, urethritis, tumors, and so on. 1. Urethral stones: urinary stones, which may cause radiating pain, may also be due to smaller stones discharged from the urethra and stuck inside the penile urethra, which can cause pain inside the penis. 2. Penile sclerosis: the cause is unknown, may be related to chronic inflammation, injury, genetic factors, immune factors, may cause pain inside the penis. 3. Prostate diseases: such as prostatitis, prostate hyperplasia, prostate cysts, etc., may also cause pain inside the penis. 4. Urethritis: Urethritis can cause congestion and swelling of the urethra, which may also cause pain inside the penis. 5. Tumors: benign tumors of the penis and neighboring organs, or malignant tumors and other occupying diseases, can also cause pain inside the penis. There may be other reasons for the pain inside the penis, it is recommended to go to the regular hospital in time to check and clarify the cause of the disease.