The invention relates to an apparatus for cutting an oval hole in the wall of a pipe. The pipe secured to a baseplate (1) of the apparatus is cut for an oval hole by means of a tool (20) having its cutter head (24) rotated about its axis while it is driven along a circular path in relation to a carriage (2) of the apparatus. The carriage (2) is mounted on the baseplate (1) by way of linear runners (3). Adapted for rotation along with a drive pulley (4) of the tool (20) is a cogged wheel (10), which through the transmission of a cam lever (11) is adapted to drive a shaft (12) having its rotational motion transmitted on the one hand to drive a gear (22) and on the other hand to work the carriage (2) back and forth in relation to the baseplate (1), a round-trip displacement (2xa) being equal to a difference between the major axis and the minor axis of a desired ellipse.