A toner cartridge includes a housing, a photosensitive drum, a connecting unit having a coupling member rotatable about a second imaginary axis, and a linking unit disposed on the photosensitive drum and rotatable about a first imaginary axis. When the coupling member is at a first position, the first and second imaginary axes are not parallel, and the coupling member doesn't contact the linking unit. When the toner cartridge is installed in an electronic imaging device and the coupling member is moved to a second position, the first and second imaginary axes are coaxial, the coupling member and the linking unit are engaged and driven to rotate by the electronic imaging device, thereby transmitting rotary kinetic energy to the photosensitive drum. Because the coupling member is movable between the first and second positions, the toner cartridge is installed in and removed from the electronic imaging device easily and smoothly.