A hot-pluggable optical transceiver capable of being inserted into an apparatus is equipped with an optical reception circuit; an optical transmission circuit; a signal processing circuit; a nonvolatile memory; a control unit controlling each of the portions of the transceiver; an insertion detection terminal; a reset terminal; and an alarm terminal. When the insertion detection terminal has a voltage that is smaller than a predetermined value, the control unit is allowed to receive the reset signal from the apparatus through the reset terminal. When the insertion detection terminal has a voltage that is larger than the predetermined value, the control unit is allowed to load new software by receiving a clock signal from the apparatus through the reset terminal and receiving a data signal synchronized with the clock signal from the apparatus through the alarm terminal and to store the new software in the nonvolatile memory.