The present invention provides the stress detection method for force sensor device with multiple axis sensor device and force sensor device employing this method, whose installation angle is arbitrary. The stress detection method includes, first and second force sensors whose detection axes are orthogonal to each other. When the detection axis of first force sensor forms angle θ with direction of detected stress Ax, and the stress component of direction perpendicular to direction of the detected stress Ax is Az, output Apx of the axis direction of first force sensor is found as Apx=αx (Ax×cos θ+Az×sin θ), and output Apz of the axis direction of the second force sensor is found as Apz=αz (Ax×sin θ+Az×cos θ), and, when αx and αz are detection sensitivity coefficients of first and second force sensors respectively, the detection sensitivity coefficient αz of second force sensor is set as αz=αx tan θ, and the detected stress Ax is found as Ax=(Apx−Apz)/αx(cos θ−tan θ×sin θ).