A method of controlling a portable information terminal comprises causing the portable information terminal to display first operation screen data which is obtained by wireless communication with a medical diagnostic imaging apparatus and includes graphic data for reception of an operation from an operator and second operation screen data which is read to the portable information terminal and includes graphic data for reception of an operation from the operator, and causing the portable information terminal to generate, in accordance with the operations for the displayed first operation screen data and the displayed second operation screen data, a command signal for causing the medical diagnostic imaging apparatus to execute functions corresponding to the operations.