A magnetic tape cartridge and A magnetic tape cartridge recording/reproducing apparatus, which can prevent a magnetic tape from being charged to avoid damage of a magnetic head while lowering the resistance of the magnetic tape and maintaining optimum electromagnetic conversion properties. A tape reel (7) is formed from a conductive material, and one end portion of a magnetic tape (6) connected to a reel hub (7B) has a surface resistivity [.OMEGA./sq] in the order of 10.sup.7 or less. In the magnetic tape (6) having a multilayer structure which comprises a magnetic layer (23), a nonmagnetic conductor layer (22), a plastic film (21), and a back coat layer (24) from the magnetic surface (6M) side, even when the surface resistivity of the magnetic layer (23) exceeds 10.sup.7 .OMEGA./sq, the magnetic layer (23) is removed and the exposed nonmagnetic conductor layer (22) is connected to the reel hub (7A), thus lowering the resistance of the magnetic tape while maintaining optimum electromagnetic conversion properties.