A thin-film magnetic head with which an error rate is decreased due to a reduction of a jitter without significant decrease in write field, is provided. The head comprises at least one inductive write head element comprising: a main magnetic pole layer having an inner saturation magnetic flux density varying from both side end surfaces in a track-width direction and a leading end surface, toward a center portion in the track-width direction of a trailing end surface; an auxiliary magnetic pole layer; and at least one coil layer, a curvature width W.sub.C of a contour line of a write field adjacent to a trailing edge on an ABS side of the main magnetic pole layer satisfying the following expression: -0.15*W.sub.T.ltoreq.W.sub.C<12 where W.sub.T is a track width and a unit of W.sub.C and W.sub.T is nanometer.