A method of transurethral local anesthesia includes: a step I of inserting a flexible ultrasound endoscope having a treatment instrument channel into a urethra or a urinary bladder; a step II of identifying a region to be anesthetized by ultrasound observation using the ultrasound endoscope; a step III of leading an injection needle out from the treatment instrument channel and injecting an anesthetic drug into the region to be anesthetized while performing ultrasound observation using the ultrasound endoscope; a step IV of extracting the ultrasound endoscope from the urethra; and a step V of inserting, after the step IV, an endoscope and/or a treatment instrument into the urethra or the urinary bladder and performing transurethral treatment.