In a flexible OLED device production method, after an intermediate region and flexible substrate region of a plastic film of a multilayer stack are divided, the interface between the flexible substrate region and glass base is irradiated with laser light. The multilayer stack is separated into first and second portions while the multilayer stack is kept in contact with the stage. The first portion includes a plurality of OLED devices in contact with the stage. The OLED devices include a plurality of functional layer regions and the flexible substrate region. The second portion includes the glass base and intermediate region. The laser light is formed from a plurality of arranged laser light sources and irradiation intensity for at least part of the interface between the intermediate region and the glass base is lower than the irradiation intensity for the interface between the flexible substrate region and the glass base.