An optical communication apparatus comprises an optical transmitter (1) which emits light signals corresponding to external electric signals (11) using light emitted from a short-wavelength light-emitting element (14) such as a yellow light-emitting diode of maximum wavelength in a range of 560-590 nm or a green light-emitting diode of maximum wavelength in a range of 490-550 nm; a plastic fiber (2) including a methacrylate polymer core free from benzene rings and having one end connected optically with the short-wavelength light-emitting element (14), the core containing less than 5 ppm free sulfur; and an optical receiver (3) having a photodetector element (31) connected optically with the other end of the plastic fiber (2) and adapted to producing an output electric signal (35) in accordance with the output from the photodetector element (31).