Provided is an organic light-emitting device having little apparent deterioration of a durable luminance. The organic light-emitting device includes a hole transport layer and a light-emitting layer which are located in a predetermined order between a reflection electrode for reflecting light and an electrode for transmitting light, the hole transport layer being in contact with the reflection electrode and made of an organic compound, and the light-emitting layer being made of an organic compound, wherein an optical film thickness L of the hole transport layer is set in a range of 0.25λ×(2n −1.7) to 0.25λ×(2n−1.3), where λ indicates an emission wavelength and n indicates a positive integer.