The invention discloses an inertial sensor device, which is used to be connected with a hand-held electronic device. The inertial sensor device comprises an accelerometer module, a gyroscope module, a connector module and a memory module, wherein the accelerometer module is used for generating acceleration sensing signals corresponding to X, Y and Z directions; the gyroscope module is used for generating angular acceleration sensing signals corresponding to X, Y and Z axes; the connector module is provided with a plug used to be plugged in a joint connector of the hand-held electronic device; the memory module is used for continuously receiving and recording acceleration sensing signals and the angular acceleration sensing signals generated from the accelerometer module and the gyroscope module, as well as digital sensing signals generated from a microprocessing control unit. The inertial sensor device is conveniently connected and disconnected with the hand-held electronic device, so that a user can use body motions to control a special cursor on an electronic game picture or a graphical user interface.