PURPOSE: A composition, consisting of a resol resin, soft ferrite, and glass fibers, and having improved heat and metal corrosion resistance, amplification of magnetic flux, shielding property and moldability.

CONSTITUTION: A phenolic resin composition obtained by incorporating 5W 15pts.wt. resol resin with 75W90pts.wt. soft ferrite and 5W10pts.wt. glass fibers. A solid resol having 400W800 number-average molecular weight is preferred for the resol resin. Soft ferrite having ≤20μm particle diameter and nickel based (≤1MHz electromagnetic waves) or manganese based (20kHzW1MHz electromagnetic waves) is preferred for the soft ferrite. Glass fibers primarily treated with a silane coupling agent are preferred for the glass fibers.