Abstract: A library apparatus having an accessor equipped with a bar code reader. The library apparatus includes a recording medium drive unit for writing and reading data to and from a recording medium cartridge; a cartridge entry unit for entering recording medium cartridges into the apparatus; and an automatic cartridge exit unit for automatically ejecting recording medium cartridges from inside the apparatus. The accessor transports cartridges through the cell unit, the recording medium drive unit, the cartridge entry unit and the automatic cartridge exit unit. The library apparatus also includes a door for allowing a large number of recording medium cartridges to enter all at once into the cells of a given cell column of the cell unit. Because the accessor is equipped with the bar code reader, the bar code of each cartridge is read thereby every time a cartridge is taken out of its cell by the accessor.