To provide dust collecting facilities of an automated guided vehicle, for simplifying the facility, reducing construction cost and maintenance cost of the facility, and improving the collecting efficiency of generated dust, by collecting generated dust in traveling of an automated guided vehicle by making use of differential pressure between the inside and the outside of a clean room.

A dust collecting device 6 for introducing air of a ceiling upper chamber B into a clean room A through a filter is arranged on a ceiling 1 to collect generated dust in traveling of an automated guided vehicle 3 having a travelling truck 3A traveling in a space 20 formed on a traveling rail 2 laid along the ceiling 1, vent ports 20a, 20b communicated with a ceiling upper chamber B are formed on the traveling rail 2, and air in the clean room A is sucked into the space 20 formed on the traveling rail 2, and this sucked air generates the circulating air flow to be introduced from the vent ports 20a, 20b to the ceiling upper camber B.