To provide an optical memory capable of extending a storage time without sacrificing efficiency, compared with a conventional single loop type optical memory.

This optical memory is formed by connecting an optical transmission path 11, a selective light amplifier 12, a wavelength selection means 61, and a coupling part 3 introducing optical pulse inputted from the outside and outputting the circulated optical pulse to the outside in a ring shape. The optical memory comprises a saturated absorber 5 adapted so that the light transmission coefficient is small when the input optical pulse is in a space state, and the light transmission coefficient is large when the input optical pulse in a mark state.