An earphone antenna comprising: - an earphone cable (41, 42) including a pair of first signal lines (41A, 41B, 42A,42B) which are insulation-coated for supplying an audio signal to an earphone (40L, 40R); - a shielded cable including a coaxial cable, a second signal line (25L, 25R) for an audio signal which is insulation-coated, and an insulation-coated grounding wire, the coaxial cable having a central conductor for passing a high frequency signal, being coated with an insulator and further covered with a first shield wire, the coaxial cable, the second signal line (25L, 25R) and the insulation-coated grounding wire being covered with a second shield wire via an insulation material; - a multipin conncetor arranged on one end of said shielded cable and adapted to electrically connect the shielded cable to a main body of a radio equipment, wherein the second shield wire is not connected to said multipin connector; and - a connection block which connects the other end of said shielded cable to said earphone cable (41, 42), the connection block including a substrate with a ground formed thereon; wherein in said connection block: - said grounding wire is connected to said ground, and said pair of first signal lines (41A, 41B, 42A, 42B) of said earphone cable (41, 42) are connected respectively to said second line (25L, 25R) for said audio signal and to said ground via high frequency chokes (35L, 35R, 35C) which become low impedance in the frequency range of said audio signal and high impedance in the frequency range of said high frequency signal, forming thereby audio signal transmission paths (32L, 32R); and - said said central conductor of said coaxial cable is connected to said pair of first signal lines (41A, 41b, 42A, 42B) of said earphone cable (41, 42) via capacitors (36, 36L,36R) which become high impedance in the frequency range of said audio signal and low impedance in the frequency range of said high frequency signal, and said first shield wire of said coaxial cable and said second shield wire of said shielded cable are connected to said ground, forming a sleeve antenna which includes said earphone cable (41, 42) and said second shield wire which covers the external of said coaxial cable, said second signal line (25L, 25R) for said audio signal and said grounding wire. - an earphone cable (41, 42) including a pair of first signal lines (41A, 41B, 42A,42B) which are insulation-coated for supplying an audio signal to an earphone (40L, 40R); - a shielded cable including a coaxial cable, a second signal line (25L, 25R) for an audio signal which is insulation-coated, and an insulation-coated grounding wire, the coaxial cable having a central conductor for passing a high frequency signal, being coated with an insulator and further covered with a first shield wire, the coaxial cable, the second signal line (25L, 25R) and the insulation-coated grounding wire being covered with a second shield wire via an insulation material; - a multipin conncetor arranged on one end of said shielded cable and adapted to electrically connect the shielded cable to a main body of a radio equipment, wherein the second shield wire is not connected to said multipin connector; and - a connection block which connects the other end of said shielded cable to said earphone cable (41, 42), the connection block including a substrate with a ground formed thereon; wherein in said connection block: - said grounding wire is connected to said ground, and said pair of first signal lines (41A, 41B, 42A, 42B) of said earphone cable (41, 42) are connected respectively to said second line (25L, 25R) for said audio signal and to said ground via high frequency chokes (35L, 35R, 35C) which become low impedance in the frequency range of said audio signal and high impedance in the frequency range of said high frequency signal, forming thereby audio signal transmission paths (32L, 32R); and - said said central conductor of said coaxial cable is connected to said pair of first signal lines (41A, 41b, 42A, 42B) of said earphone cable (41, 42) via capacitors (36, 36L,36R) which become high impedance in the frequency range of said audio signal and low impedance in the frequency range of said high frequency signal, and said first shield wire of said coaxial cable and said second shield wire of said shielded cable are connected to said ground, forming a sleeve antenna which includes said earphone cable (41, 42) and said second shield wire which covers the external of said coaxial cable, said second signal line (25L, 25R) for said audio signal and said grounding wire.