The electronic device of the present disclosure has a mounting section, a voltage determiner, and an attach-detach detector. The mounting section accepts a removable, externally-connected device and connects to a data line into which a unit signal having a data period for transmitting a data signal and a detection period for transmitting a detection signal is fed from the externally-connected device. The voltage determiner determines an electric potential of the data line so as to have a first logical value when the externally-connected device is detached from the mounting section. The attach-detach detector detects whether the externally-connected device is mounted on, or detached from the mounting section by detecting the detection signal of the first logical value determined by the voltage determiner or a second logical value.