An organic light emitting display device and a testing method thereof is provided. The organic light emitting display device may be used to perform a test of a sheet unit for a plurality of organic light emitting display devices formed on a mother substrate. The organic light emitting display device can separately turn off particular organic light emitting display devices. A display region includes a plurality of pixels, which are connected to scan lines and data lines. A scan driver supplies a scan signal to the scan lines. A peripheral region surrounds the display region and includes a first wiring group extending in a first direction and a second wiring group extending in a second direction. A transistor group includes a plurality of transistors, which are coupled with one end of the data lines. An on/off controller is coupled with at least one wiring of the first wiring group and at least one wiring of the second wiring group.