Abstract: This invention aims at providing a chemical sensor and a detection apparatus each of which can control a threshold voltage and achieve improvement in an electric-charge retention characteristic. A chemical sensor provides: a sensitive portion having a sensitive membrane sensitive to a chemical substance; a transistor having a floating gate and a gate insulating film; and a first potential controlling portion configured to control a potential of the floating gate in accordance with a voltage applied to the sensitive membrane. The first potential controlling portion has: a P-well region connected to the sensitive portion via a wiring line; a control insulating film formed to make contact with the P-well region; and a control floating portion placed at a position where the control floating portion faces the P-well region across the control insulating film, the control floating portion being conductive with the floating gate.