A support structure of pendulum mount type for supporting a drive device unit, by which the vertical floor vibration of a frequency band of 12 to 17 Hz is suppressed thereby to improve the riding comfort. Formula K2 = C·L1/L2·K1 is satisfied if one (RH) of mounts arranged on the right and left upper sides has a vertical dynamic spring constant (K1) whereas the other mount (LH) has a vertical dynamic spring constant (K2), the horizontal distances from the center of gravity (G) of the unit to the centers of the two mounts are (L1) and (L2), and a constant (C) is (no less than 1.3 and preferably less than 1.9). The vertical loss factor (Lf) of the mount (RH) has a peak frequency set at about 15 Hz.
