PURPOSE: To simplify the constitution of a line tracking device itself, by shifting successively the center of an optical fiber group to the detecting point of a line which is detected by the optical fiber group.

CONSTITUTION: An optical fiber group 20 containing numbers of optical fibers 19 which are set equidistantly on a microcircle circumference is attached to a tracking head 5. The light given from the group 20 is detected by a signal detection processing circuit 30 and then fed to a division multiple circuit 40 via a direction designating circuit 32. The circuit 40 shows the middle part between two fibers 19 as a line detecting point when plural adjacent fibers 19 detect simultaneously a line. At the same time, an arithmetic circuit 51 calculates the X and Y components between the center of the group 20 and the line detecting point. Based on the result of this operation, the center of the group 20 which is fed into a motor driving circuit 52 is shifted to the line detecting point.