Provided is a drilling device having a simple configuration, and being less likely to cause errors in drilling direction even when the bone density of the cancellous bone to be drilled is non-uniform. A drilling device includes a drill having a central hole formed from a front end along a rotation axis, and a guide pin inserted in the central hole from the front end, wherein the drilling direction thereof is determined by a guide pin embedded either in an embedding hole formed by a pilot hole drilling device or an embedding hole formed by a drill in one previous step.
