The invention discloses a 2M wire detector. The detector comprises a machine body. A first detection circuit matched with a core wire of a 2M wire, and a second detection circuit matched with a shielding layer of the 2M wire, are arranged in the machine body. An alarming circuit is connected between the first detection circuit and the second detection circuit. A socket is arranged on the machine body. A first power supply is arranged on the first detection circuit. A first light emitting diode is arranged between the first power supply and an upstream connection point of the core wire. A second light emitting diode is arranged between the first power supply and a downstream connection point of the core wire. A second power supply is arranged on the second detection circuit. A third light emitting diode is arranged between the second power supply and an upstream connection point of the shielding layer. A fourth light emitting diode is arranged between the second power supply and a downstream connection point of the shielding layer. A warning light emitting diode and a warning device are arranged on the alarming circuit. The detector is simple to operate, easy to use and precise and highly efficient in detection.