To obtain a radiation sensitive resin material which improves accuracy of pattern formation in a dissolving process and realizes a high integration degree by incorporating specified functional groups into the ends of polymer chains of a specified branched polymer.

This radiation-sensitive resin material is composed of a branched polymer, and the branched polymer has functional groups described below on the ends of the polymer chains. The functional groups get affective or reactive with a liquid by irradiation of electromagnetic waves or electron beams or by the chemical reaction induced by them, or the functional groups cause crosslinking reaction by irradiation of electromagnetic waves or electron beams or by the chemical reaction induced by them. The branched polymer satisfies both of two relations 500<Mn(GPC)≤200,000 and Mw/Mw(GPC)>1. In these relations, Mn(GPC), Mw(GPC) are the number average mol.wt. and the weight average mol.wt., respectively, measured by gel permeation chromatography (GPC), and Mw is the real weight average mol.wt. measured by mass spectrum method or light scattering method.