A laser processing apparatus, comprising: a light source for emitting a first laser beam; and being characterised by: a first reflection mirror adapted to reflect the first laser beam emitted by the light source onto an inner surface at an end portion of a cylinder so as to make a first part of the first laser beam contact the cylinder and a second part of the first laser beam pass an outer side of the end portion of the cylinder; a first reflector adapted to reflect the second part of the first laser beam, which has passed the outer side of the end portion, onto an outer surface of the cylinder so as to make the reflected second part contact the cylinder; and a rotator adapted to rotate the cylinder around a center of the cylinder relative to the first reflection mirror and the first reflector; wherein, in use, the end portion of the cylinder is disposed on a path of the first laser beam from the first-reflection mirror to the first reflector, and the first part of the first laser beam contacts the inner surface and at least a part of the reflected second part of the first laser beam contacts the outer surface simultaneously. a light source for emitting a first laser beam; and being characterised by: a first reflection mirror adapted to reflect the first laser beam emitted by the light source onto an inner surface at an end portion of a cylinder so as to make a first part of the first laser beam contact the cylinder and a second part of the first laser beam pass an outer side of the end portion of the cylinder; a first reflector adapted to reflect the second part of the first laser beam, which has passed the outer side of the end portion, onto an outer surface of the cylinder so as to make the reflected second part contact the cylinder; and a rotator adapted to rotate the cylinder around a center of the cylinder relative to the first reflection mirror and the first reflector; wherein, in use, the end portion of the cylinder is disposed on a path of the first laser beam from the first-reflection mirror to the first reflector, and the first part of the first laser beam contacts the inner surface and at least a part of the reflected second part of the first laser beam contacts the outer surface simultaneously. a first reflection mirror adapted to reflect the first laser beam emitted by the light source onto an inner surface at an end portion of a cylinder so as to make a first part of the first laser beam contact the cylinder and a second part of the first laser beam pass an outer side of the end portion of the cylinder; a first reflector adapted to reflect the second part of the first laser beam, which has passed the outer side of the end portion, onto an outer surface of the cylinder so as to make the reflected second part contact the cylinder; and a rotator adapted to rotate the cylinder around a center of the cylinder relative to the first reflection mirror and the first reflector; wherein, in use, the end portion of the cylinder is disposed on a path of the first laser beam from the first-reflection mirror to the first reflector, and the first part of the first laser beam contacts the inner surface and at least a part of the reflected second part of the first laser beam contacts the outer surface simultaneously.