A dual-shaft synchronous transmission device is applied to an electronic apparatus. The distance between the two shafts of the dual-shaft synchronous transmission device is shortened so that the electronic device can be thinned and lightweight. The dual-shaft synchronous transmission device includes a driver and a reactor respectively disposed on a first shaft and a second shaft and a link unit. Spur gear structures or crown gear structures are respectively disposed on the driver and the reactor. Crown gear structures or spur gear structures are respectively disposed at two ends of the link unit correspondingly engaged with the spur gear structures or crown gear structures of the driver and the reactor. When the first shaft and the driver are rotated, the driver rotates the link unit to drive the reactor and the second shaft to synchronously rotate in a direction reverse to the rotational direction of the driver.