PURPOSE: To automatically read a tachograph with no intervention of the naked eyes by reading the pictures produced on the surface of a revolving tachograph recording sheet in the form of the two-dimensional picture data with use of the electric signals based on the secondary scan carried out in the revolving direction of the tachograph and the main scan carried out in the direction orthogonal to the secondary scanning direction.

CONSTITUTION: An image pickup mechanism 30 contains the light sources 31a and 31b which radiate the beams onto the surface of a prescribed area set along the radius direction of a tachograph recording sheet P which is held on a transparent holding base 10 with the recording surface of the sheet P turned down (turned-over state), a reflector 32 which deflects the light reflected on the surface by 90°, an image forming lens 33, and a line sensor 34. Then a line diagram recorded on the surface of a tachograph is read in the form of the two-dimensional picture data produced by the electric signals via the main scan carried out in the radius direction of the sheet P and the secondary scan carried out by the revolution of the sheet P caused by the revolution of the stage 10. As a result, the tachograph can be read with no intervention of manual operations and the time and the labor required for reading/analyzing jobs can be reduced. At the same time, the processing time is extremely shortened.