PURPOSE: To interrupt the transmission of the vibration of an outboard motor to the hull side by insulation by pivotally supporting the upper holder on the tip of a link in a turnable manner around the vertical shaft.

CONSTITUTION: In operating an engine, an outboard motor is vibrated horizontally by the inertia of a piston, but since the outboard motor is supported by the lower holder 37 by means of the lower journal of the stem, vibration (a) in the lower journal nearly positioned at the impact center of the outboard motor is absorbed by the turning allowance around the horizontal pin of a bearing 36 to support the lower holder 37, and therefore, the vibration is not transmitted to the bearing 36 side. Also, since it is supported by the upper holder 31 at the upper journal of the stem of the outboard motor, horizontal vibration of the outboard motor by rocking (b) around the vertical pin 33 of the holder 31 and vibration (c) around the vertical pin 25 of a link 26 are absorbed two-stepwise, and therefore, transmission of vibration to the vertical pin 25 side pivotally supporting the link 26 does not occur.