1. An information processing apparatus comprising: a display unit configured to display a page designated by a page designation instruction of pages included in an electronic book; a voice output unit configured to, in a case of inputting a voice output instruction, sequentially output voices corresponding to respective characters in a target page being a page displayed by said display unit at an input timing of the voice output instruction, in accordance with an arrangement order of the characters; a control unit configured to determine a start character from which said voice output unit starts a voice output operation based on characters in the target page, and to control said voice output unit to sequentially output voices corresponding to characters, which include the start character and subsequent characters in accordance with the arrangement order; and a timer unit configured to measure a display continuous time of a page designated by an input page designation instruction on said display unit every time the page designation instruction is input, wherein when a page whose display continuous time is measured by said timer unit and is not less than a predetermined time, is the target page for which said voice output unit has output voices lastly, said control unit sets, as a last character, a character for which said voice output unit output a voice at an input timing of a first page designation instruction after said voice output unit starts to output voices for the target page, and controls said voice output unit to sequentially output voices, in accordance with the arrangement order, corresponding to respective characters which include a character located in the vicinity of a next character of the last character and subsequent characters in the arrangement order.