To provide an automated guided vehicle that prevents damage to a wafer from a mapping sensor when wafers contained in a buffer cassette are mapped, in an automated guided vehicle mounted with a sheet transfer device and a buffer cassette.

The automated guided vehicle 1 is equipped with the mapping sensor 24 vertically movable without contact with wafers 7 contained in the buffer cassette 5 as the contained wafers are pressed by a pressing member 25 across an opening 5a of the buffer cassette so as not to protrude from the opening 5a. The pressing member 25 serves also as a protrusion preventing means for the wafers during travel.