A bone cement injection device whereby bone cement is inserted through the skin and into bone, and can easily be separated during outflow of the bone cement into the blood vessels and spinal canal and curing. An outer insertion member has an outer needle tube having one end that is sharpened to be inserted through the skin and into bone and a partially closed part where the cross-sectional area of the internal space is reduced. A main hand grip is integrally formed on the other end of the outer needle tube and has a fastening part able to be fastened to a bone cement supply. An inner insertion member includes an inner needle rod for insertion into the other end part of the outer needle tube which opens through the main hand grip, and an auxiliary hand grip which is integrally formed on the inner needle rod.