PURPOSE: To provide a protective sheet capable of corresponding to electric wire size and combination within a wide range.

CONSTITUTION: In a protective sheet 10, in which a low melting-point material layer 10b is formed onto the surface of a high melting-point material layer 10a, a large number of flexible projection sections 11 are formed to the surface of the high melting-point material layer 10a, and said low melting-point material layer 10b is formed along the shape of the surface of the layer 10a. The protective sheet 10 is used for forming a molded insulating layer by pressing and holding the conductor connecting sections of insulated covered wires 1, 2 and insulated covered layers in the vicinity of the conductor connecting sections from both upper and lower surfaces while directing the low melting-point material layer 10b side toward the inside and melting the low melting-point material layer 10b by oscillatory waves such as ultrasonic waves under the state.