To obtain the subject composition developing excellent heat-resistance and electrical properties by including a preparatory reaction product of an epoxy compound with a phenol-modified polyphenylene ether and a cyanate compound as essential components.

This composition contains (A) a preparatory reaction product obtained by the preparatory reaction of (i) an epoxy compound having ≥2 epoxy groups in one molecule with (ii) a phenol-modified polyphenylene ether (abbreviated as PPE) obtained by the rearrangement reaction of PPE in the presence of phenols and a radical initiator and (B) a cyanate compound (preferably an aromatic compound having ≥2 cyanate groups in one molecule) as essential components. The number-average molecular weight of the component (ii) is preferably 500-7,000 and the average molecular weight of the component A is preferably 500-5,000 including the unreacted materials in the components (i) and (ii). The composition is useful for printed circuit board, etc.