PURPOSE: To provide a plunger for an inexpensive transfer molding machine, which is superior in wear resistance, by a method wherein a side sliding face of the plunger is made a build-up layer where hard particles are held through dispersion on a substrate composed of a Fe group alloy or Fi group alloy or Co group alloy or alloy of those through build-up welding of a powdery material.

CONSTITUTION: A build-up layer 2a is formed on a side sliding face after a plunger matrix heat-treated and then a pressurizing face 2c of the tip is plated with bard chromium. An alloy of a generally known ingredient is used as an alloy for a substrate and WC, TiC, TiN, TiB2, VC, SiO2 are mentioned as hard particles. A weld penetration rate is extremely low so that it is 5% or lower and delicate control in a thickness of a build-up layer is possible, in build-up welding of a powdery material. As the quality of the material can be selected regardless of manufacturing of a welding rod for the build-up welding of the powdery material, manufacturing of far highly efficient plunger is possible.