An alignment adjusting apparatus of a robot to execute conveying operations of putting and taking an object to be conveyed in and out of an accommodating shelf includes at least two reference flags to be installed in the accommodating shelf; a flag measuring unit to measure the reference flags on the robot positioned at the reference flags; and an alignment adjusting unit to adjust an alignment shift of the robot corresponding to an inclination of the robot, the inclination being obtained from a variation of a measured value of each of the reference flags by the flag measuring unit.