Abstract: A C-V(capacitance-to-voltage) conversion apparatus usable e.g. for detecting physical parameters such as pressure, distance and angle. The apparatus comprises a capacitive sensor, a C-PW(capacitance-to-pulse width) conversion circuit, and a PW-V(pulse width-to-voltage) conversion circuit. The capacitive sensor converts a physical parameter to a capacitance, but has a non-linear conversion characteristic. The C-PW conversion circuit converts the capacitance to a pulse signal whose mean value is proportional to the capacitance, by controlling a charging-discharging cycle of the capacitive sensor and a reference capacitor. The PW-V conversion circuit converts the pulse signal to a d.c. voltage and at the same time compensates for the non-linearity of the capacitive sensor's conversion characteristic so that the d.c. voltage is proportional to the physical parameter.