A position detecting device comprising: a display unit which has a first electrode formed of a transparent conductive film, a plurality of second electrodes, and display material interposed between the first electrode and the plurality of second electrodes; a display driver configured to drive the display unit based on a video signal input to the display driver; and a position detecting section configured to detect a position indicated on the first electrode by an indicator and to output a detected position signal, wherein the display unit is configured to maintain a display state when a drive power applied between the first electrode and the second electrodes is discontinued, characterized in that the position of the indicator on the first electrode is detected by the position detecting section constantly in the absence of the video signal, and, in the presence of the video signal, the position of the indicator on the first electrode is detected by the position detecting section in a time-sharing mode with the display driver driving the display unit, wherein the display driver comprises a display driving controller configured to control the time-sharing mode of operation of the position detecting section and the display driver, wherein the display driving controller is further configured to: selectively connect the display driver or the position detecting section to the first electrode such that in a first state, in which the video signal is absent while the indicator is present, the position detecting section is driven to constantly detect an indicated position of the indicator, and, in case the video signal is input to the display driver, cause transition of the first state to a second state, in which the display driver and the position detecting section are alternately operated, wherein, in the second state, a driving time assigned to the position detecting section is longer than a driving time assigned to the display driver. a display unit which has a first electrode formed of a transparent conductive film, a plurality of second electrodes, and display material interposed between the first electrode and the plurality of second electrodes; a display driver configured to drive the display unit based on a video signal input to the display driver; and a position detecting section configured to detect a position indicated on the first electrode by an indicator and to output a detected position signal, wherein the display unit is configured to maintain a display state when a drive power applied between the first electrode and the second electrodes is discontinued, characterized in that the position of the indicator on the first electrode is detected by the position detecting section constantly in the absence of the video signal, and, in the presence of the video signal, the position of the indicator on the first electrode is detected by the position detecting section in a time-sharing mode with the display driver driving the display unit, wherein the display driver comprises a display driving controller configured to control the time-sharing mode of operation of the position detecting section and the display driver, wherein the display driving controller is further configured to: selectively connect the display driver or the position detecting section to the first electrode such that in a first state, in which the video signal is absent while the indicator is present, the position detecting section is driven to constantly detect an indicated position of the indicator, and, in case the video signal is input to the display driver, cause transition of the first state to a second state, in which the display driver and the position detecting section are alternately operated, wherein, in the second state, a driving time assigned to the position detecting section is longer than a driving time assigned to the display driver. selectively connect the display driver or the position detecting section to the first electrode such that in a first state, in which the video signal is absent while the indicator is present, the position detecting section is driven to constantly detect an indicated position of the indicator, and, in case the video signal is input to the display driver, cause transition of the first state to a second state, in which the display driver and the position detecting section are alternately operated, wherein, in the second state, a driving time assigned to the position detecting section is longer than a driving time assigned to the display driver.