Provided is an electrostatic capacitance detection circuit and an input device which restrain expansion of circuit scale and increase of power consumption, restrain influence of noise, and can stably detect tiny changes of electrostatic capacitance by high ratio of S/N. The electrostatic capacitance detection circuit (1) includes a charge amplifier (10) that has an operational amplifier (11) in which a capacitor (Cfb) is provided on a feedback path, and into which a signal including detection of electric charge of an inter-electrode capacitor (Cm) of a sensor electrode (2) and electric charge due to an external noise, and a selection switch (SW4-1, SW5-1, SW4-2, SW5-2)that can switch a direction of a capacitor that is connected to input and output terminals of the charge amplifier (10) through a feedback path that switches the direction of the capacitor (Cfb) depending on a direction of electric charge flowing in from a detection-side electrode of the sensor electrode (2), due to a drive signal applied to the sensor electrode.