To provide the subject motor support structure having resolved a problem that, for a motor mounted on the tip of a yarn feed arm, because the edge face thereof is fixed by merely clamping it via bolts, the motor fixation and/or the fixation between the motor and a gear head tend to be loosened, in view of the fact that the yarn feed arm makes a quick action/sudden halt.

This motor support structure has such a scheme that, in a yarn feed arm 7 movable between a waiting position and a feed position, having a pair of yarn feed rollers 7b and 7c and designed to feed a yarn nipped with these rollers through driving them, a motor 7e for driving the roller 7b is springily supported on the yarn feed arm, specifically one edge face in the motor's axial direction and the motor's outer circumferential surface are supported via a fixing member 75 and via a springy element (O-ring 2) on the yarn feed arm, respectively, and the support position 72s via the springy element is set apart from the center of gravity G of the motor toward the other end in the axial direction, and furthermore both the fixing member 75 and the springy element are, mounted on a common bracket 73.