A line-shaped assembly includes a heat source that includes a heat source main body extending straightly and a heat source cover member covering the heat source main body, and a tubular-shaped heat source protective member that accommodates and protects the heat source. The heat source protective member is made of resin, and includes a first tube body portion with an inner surface that has a small area per unit length in an axial direction of the heat source protective member in contact with the heat source, and a second tube body portion with an inner surface that has a contact area larger than that of the first tube body portion.