Cardiac magnetic resonance imaging (MRI) is a useful tool for detecting the arrhythmogenic substrate in cardiac sarcoidosis. We herein present a case of bipolar radiofrequency catheter ablation for ventricular tachycardia (VT) complicated with cardiac sarcoidosis, guided by pre-procedural cardiac MRI. Neither echocardiography nor endocardial voltage mapping suggested a septal VT substrate. However, MRI alone detected intramural lesions in the septum. Although application of endocardial energy failed to treat the VT, bipolar ablation targeting the potential substrate identified by MRI successfully eliminated the VT. Even when no abnormalities are depicted on echocardiography and endocardial voltage mapping, intramural scar tissue identified by cardiac MRI could be critical for VT.