A printing material cartridge mountable in a holder of a printing apparatus comprising: a mounting detection circuit including a power supply for mounting detection and a mounting current value detection section arranged to detect a detection current that flows when a cartridge set configured of N, where N is an integer of 2 or more, printing material cartridges is mounted in the holder, the mounting detection circuit being arranged to detect a mounting state of the printing material cartridge in the holder according to the detection current, wherein the printing material cartridge comprises: a storage device storing information regarding contained printing material; an electrical device for the mounting detection; and a plurality of terminals including terminals for the storage device and terminals for the electrical device; characterized in that the electrical device is: (i) arranged to be connected in parallel to the electrical device of another printing material cartridge of the cartridge set, between the power supply for mounting detection and the mounting current value detection section when the cartridge set is mounted in the printing apparatus, and (ii) configured such that the detection current that is detected at the mounting current value detection section is equal to or greater than a predetermined threshold value current when the N printing material cartridges are mounted inside the holder; and wherein the terminals for the storage device include a ground terminal and the terminals for the electrical device are not connected to the ground terminal. a mounting detection circuit including a power supply for mounting detection and a mounting current value detection section arranged to detect a detection current that flows when a cartridge set configured of N, where N is an integer of 2 or more, printing material cartridges is mounted in the holder, the mounting detection circuit being arranged to detect a mounting state of the printing material cartridge in the holder according to the detection current, wherein the printing material cartridge comprises: a storage device storing information regarding contained printing material; an electrical device for the mounting detection; and a plurality of terminals including terminals for the storage device and terminals for the electrical device; a storage device storing information regarding contained printing material; an electrical device for the mounting detection; and a plurality of terminals including terminals for the storage device and terminals for the electrical device; characterized in that the electrical device is: (i) arranged to be connected in parallel to the electrical device of another printing material cartridge of the cartridge set, between the power supply for mounting detection and the mounting current value detection section when the cartridge set is mounted in the printing apparatus, and (ii) configured such that the detection current that is detected at the mounting current value detection section is equal to or greater than a predetermined threshold value current when the N printing material cartridges are mounted inside the holder; and (i) arranged to be connected in parallel to the electrical device of another printing material cartridge of the cartridge set, between the power supply for mounting detection and the mounting current value detection section when the cartridge set is mounted in the printing apparatus, and (ii) configured such that the detection current that is detected at the mounting current value detection section is equal to or greater than a predetermined threshold value current when the N printing material cartridges are mounted inside the holder; and wherein the terminals for the storage device include a ground terminal and the terminals for the electrical device are not connected to the ground terminal.