A display device includes a power key, and at least one processor that executes following: determination processing that determines, when turning on a light source in response to a user's operation on the power key, whether a power supply supplying power is a predetermined power supply or not, and control processing that displays, when the determination processing determines that the power supply is the predetermined power supply, a power-on continuation confirmation screen and continues, in case of detection of a confirmation operation from the user according to the power-on continuation confirmation screen, lighting of the light source.