Provided is a flow path structure of a power transmission device which is capable of removing gas from a lubricating fluid guided to a fluid reservoir while suppressing an increase in a size of the entire power transmission device. A gasket (63) has an extending portion which extends toward an inside of a transmission case (31). A flow path (70) which extends from an upper portion to a lower portion and guides lubricating oil discharged from a discharge mechanism (64) to an oil reservoir is formed inside the transmission case (31) using the extending portion. The discharge mechanism (64) discharges the lubricating oil toward an inner surface of the flow path (70).