In a laser machining apparatus, a scanner is configured to scan a laser beam emitted from a laser beam emission device. A first part of a workpiece is exposed through an opening formed in the workpiece. A controller is configured to perform: acquiring shape data indicative of a shape of the workpiece; acquiring machining pattern data indicative of a machining pattern to be machined on the first part; acquiring a length of the machining pattern based on the machining pattern data; calculating an unmachinable position on a setting surface using the length and the shape data, the unmachinable position resulting from a second part of the workpiece hindering the laser beam reaching the first part, at least a part of the machining pattern being unmachinable on the first part in a state where the workpiece is set on the unmachinable position; and displaying the unmachinable position on a display.