To provide an inexpensive wire for an interdental brush having high breaking strength and high elongation properties; a manufacturing method therefor; and an inexpensive interdental brush superior in bending strength and rigidity.

A wire rod for the interdental brush has a chemical composition comprising, by wt.%, 0.08% or less C, 3.0-5.0% Si, 3.0% or less Mn, 4.0-12.0% Ni, 12.0-24.0% Cr, 0.9-2.0% Mo, 0.5-2.0% Cu and the balance iron with an unavoidable impurities. The method for manufacturing the wire for the interdental brush comprises final-drawing the above wire rod with a reduction of 70% or higher, and final stress-relief heat-treating it at 800-1,050°C.