Saddle block is effective for perineal cancer pain. However, there is substantial risk of relative opioid overdose and opioid withdrawal syndrome following sudden relief of pain. We report a case of successful management of saddle block for intractable anal pain in a patient who required high-dose opioids. A patient in his forties was referred to our hospital due to intractable anal pain. 40 mg/day of transdermal fentanyl was administrated, but numerical rating scale (NRS) rated 8–10/10. Saddle block was scheduled because of insufficient pain relief. To avoid relative opioid overdose and opioid withdrawal syndrome, we switched from transdermal fentanyl to oxycodone injection. We performed saddle block while reducing oxycodone injection. NRS rated 0/10 just after saddle block without any adverse effects. Although we performed saddle block with tetracaine or phenol glycerin several times during the hospitalization, no significant block-related adverse effects were encountered.