A differential signal cable for transmitting high-speed digital differential signals of several Gbit/s or more is provided to minimize characteristic impedance mismatch and to repress increase in the skew, or increase in disturbance due to differential-mode to common-mode conversion. A differential signal cable comprises two insulated wires arranged parallelly in a contact, each of said two insulated wires comprising a conductor and an insulator jacketing the conductor; a fusion layer provided on the surface of each of said two insulated wires; a drain wire placed longitudinally in a recess created in the interstice between said two insulated wires; and a shield tape lapping around said two insulated wires and said drain wire together, wherein a surface of said insulator of each of said two insulated wires is partially deformed so as to have a flat portion and said two insulated wires are fused each other at said flat portions.