A method of correcting ultrasound images, the method including the operations of, by an ultrasound output unit, outputting an ultrasound signal to a target object; obtaining an mechanical index (MI) map indicating a correlation between depth values according to a travel direction of the ultrasound signal, and MI values by the ultrasound signal; and adjusting a gain value of an ultrasound echo signal corresponding to the ultrasound signal by using a reverse MI map that is obtained by reversing the MI map, so as to allow the MI values, which are displayed on the MI map, to be a virtually constant MI value with respect to the depth values.