A polymer compound includes a carboxyl group and a siloxane chain and is obtained in the presence of an acid catalyst by condensation of at least; (I) a siloxane compound having phenol groups at both terminals, as shown by formula (1), (II) phenols shown by formula (2) and/or phenols shown by formula (3), and (III) one or more kinds of aldehydes and ketones shown by the following general formula (4). The polymer compound can be used suitably as a base resin of a chemically amplified negative resist composition with which the problem of delamination generated on metal wires, an electrode, and a substrate, can be improved, and with which a fine pattern can be formed without generating a scum and a footing profile in the pattern bottom and on the substrate, using a widely used aqueous 2.38% TMAH solution as a developer.