An image processing apparatus includes an image processor; an audio input to input a user's speech; a storage to store at least one simple sentence voice command and an operation corresponding to the simple sentence voice command; a communication device to communicate with a server that analyzes a descriptive sentence voice command and determine an operation corresponding to the descriptive sentence voice command; an audio processor to process a first voice command corresponding to the speech and conduct the operation corresponding to the simple sentence voice command if the first voice command is the simple sentence voice command, and to transmit the first voice command to the communication device if the first voice command is not the simple sentence voice command; and a controller configured to display a first guide image which recommends the simple sentence voice command stored in the storage if the corresponding operation for the first voice command determined by the server is identical to one of the at least one simple sentence voice command stored in the storage.