A vitreous body cutter that allows wide movement of an opening position at the end part of a pipe even when the pipe is thin and that allows suction of vitreous bodies etc. in a wide range. The vitreous body cutter includes: a pipe having an opening on the side of an end part; a cutter, which slides along the inner surface of the pipe; a power output section, which is connected to the pipe and slides the cutter; and an outer case, through which the pipe passes, and which includes the power output section inside; and further includes a joint for connecting the outer case to a cannula attached to an eyeball. The protrusion length of the pipe from the outer case can be changed.