A foam coaxial cable, comprising an inner conductor ( 1 ), a foam insulating layer ( 2 ) formed on the outer periphery of the inner conductor ( 1 ), an outer conductor ( 3 ) formed on the outer periphery of the foam insulating layer ( 2 ), and an outer cover ( 4 ) formed on the outer periphery of the outer conductor ( 3 ). A skin layer ( 11 ) having a generally complete round outline is formed on the outer periphery of the foam insulating layer ( 2 ). Thus, the productivity of the foam insulating layer ( 2 ) can be increased by increasing the accuracy of the characteristic impedance values of the cable while increasing the flexibility and mechanical strength of the cable.