A capacitance detection device comprising: a capacitor array constituting a variable capacitance capacitor, said capacitor array comprising a plurality of capacitors of different capacitances which are connected in parallel to each other, said capacitor array having a combined capacitance (Cs); a detection capacitor, connected to an electrode, (12; 34) whose capacitance (Cx) is to be detected, said detection capacitor being connected in series to the capacitor array; and a control circuit (18, 18a, 18b, 18c, 18d, 18e), comprising: a detection unit configured to detect an intermediate potential (Vout), which is a potential of capacitive voltage division of a power supply, based on the combined capacitance (Cs) and the capacitance of the detection capacitor; a switching control unit configured to selectively switch the plurality of capacitors between an ON state and an OFF state to change the combined capacitance (Cs) of the capacitor array while the intermediate potential is being detected; an acquisition unit configured to acquire, as a first combined capacitance and a second combined capacitance, any one of the combined capacitances in a vicinity where a magnitude relationship between the intermediate potential and a predetermined reference potential (Vref) is inverted; a calculation unit configured to calculate an estimated combined capacitance (Cse) of the capacitor array when the intermediate potential (Vout) coincides with the reference potential (Vref), based on a first intermediate potential (Vout1) and a second intermediate potential (Vout2) that are the intermediate potentials when the combined capacitance is the first combined capacitance and the second combined capacitance, respectively; and a derivation unit configured to derive the capacitance of the detection capacitor as a detection capacitance, based on the estimated combined capacitance. a capacitor array constituting a variable capacitance capacitor, said capacitor array comprising a plurality of capacitors of different capacitances which are connected in parallel to each other, said capacitor array having a combined capacitance (Cs); a detection capacitor, connected to an electrode, (12; 34) whose capacitance (Cx) is to be detected, said detection capacitor being connected in series to the capacitor array; and a control circuit (18, 18a, 18b, 18c, 18d, 18e), comprising: a detection unit configured to detect an intermediate potential (Vout), which is a potential of capacitive voltage division of a power supply, based on the combined capacitance (Cs) and the capacitance of the detection capacitor; a switching control unit configured to selectively switch the plurality of capacitors between an ON state and an OFF state to change the combined capacitance (Cs) of the capacitor array while the intermediate potential is being detected; an acquisition unit configured to acquire, as a first combined capacitance and a second combined capacitance, any one of the combined capacitances in a vicinity where a magnitude relationship between the intermediate potential and a predetermined reference potential (Vref) is inverted; a calculation unit configured to calculate an estimated combined capacitance (Cse) of the capacitor array when the intermediate potential (Vout) coincides with the reference potential (Vref), based on a first intermediate potential (Vout1) and a second intermediate potential (Vout2) that are the intermediate potentials when the combined capacitance is the first combined capacitance and the second combined capacitance, respectively; and a derivation unit configured to derive the capacitance of the detection capacitor as a detection capacitance, based on the estimated combined capacitance. a detection unit configured to detect an intermediate potential (Vout), which is a potential of capacitive voltage division of a power supply, based on the combined capacitance (Cs) and the capacitance of the detection capacitor; a switching control unit configured to selectively switch the plurality of capacitors between an ON state and an OFF state to change the combined capacitance (Cs) of the capacitor array while the intermediate potential is being detected; an acquisition unit configured to acquire, as a first combined capacitance and a second combined capacitance, any one of the combined capacitances in a vicinity where a magnitude relationship between the intermediate potential and a predetermined reference potential (Vref) is inverted; a calculation unit configured to calculate an estimated combined capacitance (Cse) of the capacitor array when the intermediate potential (Vout) coincides with the reference potential (Vref), based on a first intermediate potential (Vout1) and a second intermediate potential (Vout2) that are the intermediate potentials when the combined capacitance is the first combined capacitance and the second combined capacitance, respectively; and a derivation unit configured to derive the capacitance of the detection capacitor as a detection capacitance, based on the estimated combined capacitance.