A communication device equipped with a first unit and a second unit that is detachably attached to said first unit and that is able to communicate with said first unit; said first unit being provided with at least a first display unit, a transmitter unit that outputs an input voice signal, and a receiver unit that reproduces an input voice signal; and said second unit being provided with at least a second display unit; said communication device comprising: an input unit that accepts operation input; a communication unit that, upon receiving input indicating that a voice call is to be made, transmits a voice signal that is output by said transmitter unit to a communication partner by way of a network and applies as input to said receiver unit a voice signal from said communication partner that is received by way of said network; a detection unit that detects whether or not said first unit and second unit are in a separated state; and a control unit that executes an application in accordance with input by way of said input unit, and when not making a voice call, displays images that correspond to the execution of said application on said first and second display units (111, 131), and when input is received indicating that a voice call is to be made, and moreover, when the detection result of said detection unit indicates that said first unit and second unit are in the separated state, displays images that correspond to the execution of said application on said second display unit, wherein: said first unit and second unit are linked in a linked state that can be opened or closed; said detection unit further detects the opened/closed state of said first unit and second unit; and when input is received indicating that a voice call is to be made, and moreover, when the detection result of said detection unit indicates the fully-opened state in which said communication device is folded such that the outer sides of said first display unit and said second display unit face each other, said control unit causes a voice call to be started and turns OFF the display of said first display unit and causes any image to be displayed on said second display unit. an input unit that accepts operation input; a communication unit that, upon receiving input indicating that a voice call is to be made, transmits a voice signal that is output by said transmitter unit to a communication partner by way of a network and applies as input to said receiver unit a voice signal from said communication partner that is received by way of said network; a detection unit that detects whether or not said first unit and second unit are in a separated state; and a control unit that executes an application in accordance with input by way of said input unit, and when not making a voice call, displays images that correspond to the execution of said application on said first and second display units (111, 131), and when input is received indicating that a voice call is to be made, and moreover, when the detection result of said detection unit indicates that said first unit and second unit are in the separated state, displays images that correspond to the execution of said application on said second display unit, said first unit and second unit are linked in a linked state that can be opened or closed; said detection unit further detects the opened/closed state of said first unit and second unit; and when input is received indicating that a voice call is to be made, and moreover,