To allow stable traveling by a simple and inexpensive device without using a lot of magnetic sensor elements, in an automatic carrier traveling unattendedly along a magnetic tape laid along a prescribed route to convey an assembled part and the like mounted thereon to a prescribed site in a manufacturing factory or the like.

The two magnetic sensor elements 8, 8 for detecting magnetic force of the magnetic tape 6 are attached to the automatic carrier 1, the both sensor elements 8, 8 are paired with a space narrower than a width of the magnetic tape, and a controller 5 is provided to control motors 4, 4 for driving wheels 2, 2 by receiving an output of the both sensor elements 8, 8.