A multi link type piston-crank mechanism comprises an upper link that has one end pivotally connected to a piston of the engine through a piston pin, a lower link that is pivotally connected to the other end of the upper link through an upper pin and rotatably disposed on a crank pin of a crankshaft of the engine; and a control link that has a base end part swingably held by a body of the engine and a leading end pivotally connected to the lower link through a control pin. An axis of the piston pin is offset relative to an axis of the piston in thrust and counter thrust directions. When the piston comes to BDC, a part of the piston takes a position below a lower edge of a corresponding cylinder of the engine and the upper pin is offset relative to the axis of the piston pin in the same direction as a pin offset direction in which the axis of the piston pin is offset in the thrust and counter thrust directions relative to the axis of the piston.