We propose a trajectory planning method for a robot hand which is composed of non-contact suction devises using a fluid-dynamics phenomenon. As the hand cannot constrain the object in the tangential direction, sideslip occurs due to the inertial force when the object is transferred horizontally. The hand trajectory is planned so that the hand is inclined to suppress the sideslip by balancing the inertial force with the gravity. Experimental results using a linear slider that emulates a 1-dof object show that the proposed method can reduce the sideslip.