The writing input apparatus includes a touch panel input device, an input detector that detects touch input to the touch panel input device, a touch-pressure detector that detects a touch pressure applied to the touch panel input device and corresponding to the touch input detected by the input detector, a tilt angle detector that detects a tilt angle with a horizontally placed state of the touch panel input device being a reference, and an input characteristic determination device that determines an input characteristic corresponding to the touch input on the basis of the touch pressure detected by the touch-pressure detector and the tilt angle detected by the tilt angle detector.