Generation of impurity ions is prevented or reduced in a carbon ion generating device in which a laser-driven ion acceleration system is employed. A carbon ion generating device generates a carbonized region by irradiating a film made of an organic compound with a first laser beam, and generates carbon ions by irradiating at least a part of the carbonized region with a second laser beam.

Generation of impurity ions is prevented or reduced in a carbon ion generating device in which a laser-driven ion acceleration system is employed. A carbon ion generating device generates a carbonized region by irradiating a film made of an organic compound with a first laser beam, and generates carbon ions by irradiating at least a part of the carbonized region with a second laser beam.