Although selective serotonin reuptake inhibitors（SSRIs）and cognitive behavioral therapy（CBT）are first‒line treatments for obsessive‒compulsive disorder（OCD）, response rates to these therapies are 40‒60％. There may be many treatment‒refractory patients who do not respond to several SSRIs and intensive CBT treatment. The current treatment guidelines suggest various strategies for treatment‒refractory cases, but there is no established evidence for most of them. Augmentation therapies with antipsychotics and glutamate modulator drugs have yielded some supporting evidence. When all drugs and CBT are ineffective, non‒pharmacological treatment including deep brain stimulation（DBS）should be applied. However, it is necessary to establish criteria for treatment‒refractory patients and standardize conventional treatment before neuromodulation treatment is applied in Japan.