The invention provides an input device free of the problem of the gravity exerted on the acceleration sensor when the input device inclines from the proper position and enabling reduction of the computational complexity, a controller, a control system , and its control method. An MPU (19) of an input device (1) corrects angular velocity values (omega psi, omega theta) by rotational coordinate transform corresponding to a calculated roll angle to obtain corrected angular velocity values (second and first corrected angular velocity values) (omega psi', omega theta') (step 103). With this, even if the user moves the input device inclined with respect to the axis along the gravity direction (hereinafter referred to as 'the vertical axis') around the Z-axis, the influence of the gravitational acceleration components in the X'-axis and Y'-axis directions occurring because of the inclination can be eliminated.
Input device, controller, control system, control method, and hand-held device