To realize a high speed vehicle body with a simple controlling method so as to comply with a speedup of a line tracing robot by using a spherical body driving device having an omnidirectional moving characteristic for a front wheel of a robot vehicle body.

In this line tracing robot provided with a line detector in the vehicle body front part, the robot vehicle body is constructed by arranging the spherical body driving device, in which the side face of a spherical body is pressingly driven by means of driving rollers, for the front wheel and arranging two wheels turning independently of each other for rear wheels. For the driving device in the vehicle body, the spherical body driving device, which is constructed so that its four driving rollers are arranged in the outer circumference of the spherical body at angle intervals of 90 degrees mutually and the opposite two driving rollers are paired with each other for pressingly driving the spherical body, is used, and in the line tracing robot, the spherical body driving device is installed to the vehicle body board so that one of the pairs crosses the advancing direction at right angles.