A three-dimensional drive device comprising: a hollow shaft; a first motor for rotating the hollow shaft in a circumferential direction; a first spur gear having a central axis common to a central axis of the hollow shaft, arranged in a center of the hollow shaft; a second motor for rotating the first spur gear in the circumferential direction; a bevel gear meshing with the first spur gear, arranged within the hollow shaft; and a second spur gear meshing with the bevel gear, arranged within the hollow shaft, and having an axis of rotation orthogonal to the central axis of the hollow shaft, the bevel gear and the second spur gear being to turn upon moving in the circumferential direction of the hollow shaft along with rotation of the hollow shaft, wherein the first spur gear has a hollow structure (16,21,22) on a side of the central axis; and the three-dimensional drive device further comprises a light source for emitting light in a direction of the central axis of the first spur gear; and a mirror attached to the axis of rotation of the second spur gear for reflecting light emitted from the light source, an angle of a reflecting surface thereof being changed by rotation of the second spur gear characterized in that a light reception unit provided along with the light source for receiving return light of the light emitted from the light source; and an outside condition detection unit for detecting a condition of the outside on the basis of a radiation direction of the light emitted from the light source and radiated to the outside as well as a result of a comparison between the light emitted from the light source and the return light received by the light reception unit, wherein a wall surface formed along an outer periphery of the hollow shaft and having a height varying according to a position in the circumferential direction. a hollow shaft; a first motor for rotating the hollow shaft in a circumferential direction; a first spur gear having a central axis common to a central axis of the hollow shaft, arranged in a center of the hollow shaft; a second motor for rotating the first spur gear in the circumferential direction; a bevel gear meshing with the first spur gear, arranged within the hollow shaft; and a second spur gear meshing with the bevel gear, arranged within the hollow shaft, and having an axis of rotation orthogonal to the central axis of the hollow shaft, the bevel gear and the second spur gear being to turn upon moving in the circumferential direction of the hollow shaft along with rotation of the hollow shaft, wherein the first spur gear has a hollow structure (16,21,22) on a side of the central axis; and the three-dimensional drive device further comprises a light source for emitting light in a direction of the central axis of the first spur gear; and a mirror attached to the axis of rotation of the second spur gear for reflecting light emitted from the light source, an angle of a reflecting surface thereof being changed by rotation of the second spur gear characterized in that a light reception unit provided along with the light source for receiving return light of the light emitted from the light source; and an outside condition detection unit for detecting a condition of the outside on the basis of a radiation direction of the light emitted from the light source and radiated to the outside as well as a result of a comparison between the light emitted from the light source and the return light received by the light reception unit, wherein a wall surface formed along an outer periphery of the hollow shaft and having a height varying according to a position in the circumferential direction.