An information processing apparatus comprising; a touch detection unit configured to detect touch operations of a user on a touch screen using a manipulation object, and to output information including a detected pressure corresponding to the respective touch operations to a determination unit and an operation control unit; the determination unit configured to determine which of two or more input states a user operation belongs to by comparing the detected pressure with a threshold value (Pth); determine that the user operation belongs to a first input state in a first time period when the detected pressure is determined to be equal to or less than the threshold value (Pth); determine that the user operation belongs to a second input state in a second time period when the detected pressure is determined to attain a value more than the threshold value (Pth); determine that the user operation from the point of time when the determination that the detected pressure of the user operation attains a value more than the threshold value remains in the second input state until the manipulation object is released from the touch screen, and to determine that the user operation belongs to the first input state after releasing of the manipulation object from the touch screen; and the operation control unit is configured to enable or disable a limitation imposed on operation with a user interface displayed on the touch screen, in accordance with the state of the user input determined by the determination unit, wherein the limitation is that a number of candidate selectable parameter values that are user-selectable in the first input state is less than a number of candidate selectable parameter values that are user-selectable in the second input state. a touch detection unit configured to detect touch operations of a user on a touch screen using a manipulation object, and to output information including a detected pressure corresponding to the respective touch operations to a determination unit and an operation control unit; the determination unit configured to determine which of two or more input states a user operation belongs to by comparing the detected pressure with a threshold value (Pth); determine that the user operation belongs to a first input state in a first time period when the detected pressure is determined to be equal to or less than the threshold value (Pth); determine that the user operation belongs to a second input state in a second time period when the detected pressure is determined to attain a value more than the threshold value (Pth); determine that the user operation from the point of time when the determination that the detected pressure of the user operation attains a value more than the threshold value remains in the second input state until the manipulation object is released from the touch screen, and to determine that the user operation belongs to the first input state after releasing of the manipulation object from the touch screen; and the operation control unit is configured to enable or disable a limitation imposed on operation with a user interface displayed on the touch screen, in accordance with the state of the user input determined by the determination unit, wherein the limitation is that a number of candidate selectable parameter values that are user-selectable in the first input state is less than a number of candidate selectable parameter values that are user-selectable in the second input state.