A portable display device transitions between a first and second state. The device has a display portion, a power source for supplying power in the first state and supplying less power in the second state than in the first state, a controller that drives the display portion, an operation portion that executes commands, and a mode storage portion that stores one of a first and second mode. The first mode corresponds to displaying preset information, and the second mode corresponds to particular information to be continuously displayed. The particular information is information displayed in the display portion when the device is in the first state. When the device is in the second state, the preset information is displayed in the display portion when the first mode is stored in the mode storage portion, and the particular information is continuously displayed when the second mode is stored in the mode storage portion.