The invention relates to a device (1) for drilling holes in the axial and radial direction of a blade root of a wind turbine, wherein the device comprises: —a first base (2), which is to be stationary positioned on the ground; —a second base (3), which is moveably mounted to the first base (2) and movable along a first direction; —first drive means for positioning the second base (3) along the first direction; —a rotary arm (4), which is pivotally mounted to the second base (3) around a main axis (5); —second drive means for rotating the rotary arm (4) around the main axis (5); —wherein the rotary arm (4) comprises a guide track (7) which extends from a first outer end to a second outer end of the rotary arm (4) thereby passing the main axis (5); —first drilling means (8) moveably arranged on the guide track (7), comprising a first drilling tool (8-1) for drilling holes in a second direction (8-2), which second direction (8-2) is perpendicular to the main axis (5) and—third drive means for positioning the first drilling means (8) along the guide track (7); —second drilling means (9) mounted on the rotary arm (4), comprising a second drilling tool for drilling holes in a third direction (9-2), which third direction (9-2) is parallel to the main axis (5).