Brain bulging is an unfavorable outcome in patients with brain swelling who require decompressive craniectomy (DC) to control elevated intracranial pressure (ICP). Although several previous studies have described methods for reducing the operation time during DC in these patients, few have proposed a technique for controlling brain protrusion. Here we describe an effective and simple method for external reduction of ICP and discuss its suitability for patients at risk of brain bulging during DC. After craniectomy, crank-shaped lines extending from a central square dural canopy are all marked on the dura. As the incisions are made, pressure from the swelling brain opens the lines and the protruding cortical surface forms dural windows. The square canopy gradually rotates as it stretches, and along with the remaining dura, functions to gently support and compress the cortex. In the case of insufficient decompression, the incision lines can be extended to further reduce ICP. As the parenchyma is accessible to the surgeon, hematoma removal can be performed through the dural windows. In initial experience of four patients who underwent this technique, ICP was controlled in all cases after surgery and no adverse events occurred. The crank-shaped dural incision method is a simple, quick, and effective technique for external reduction of ICP in patients at risk of brain bulging that is intuitive in the emergency situation and thus can be performed even by relatively inexperienced neurosurgeons.