A drive transmission mechanism for transmitting torque between two or more rotary shafts in synchronization with one another without need for lubrication thereby eliminating occurrence of oil contamination, and an oil-free fluid machine equipped with the mechanism, are provided. A magnetic drive disk and a synchronization gear are attached to a rotary shaft connected to a drive motor, a magnetic drive disk and a synchronization gear is attached to a rotary shaft, torque transmission from the rotary shaft to the rotary shaft is carried out in two ways, via the magnetic drive disks and via the synchronization gears and at least one of the synchronization gears is made of plastic material. With the construction, torque transmit load between the rotary shafts via the synchronization gears is decreased, and a plastic gear or gears can be adopted for synchronization gears without reducing life of the gears without need for lubrication oil.