a solid electrolyte layer including positive charge carriers to which detection-target gas is to coordinate and has a contact plane to be in contact with the detection-target gas;

a first electrode and a second electrode, both of which are arranged on a plane of the solid electrolyte layer opposite to the contact plane of the solid electrolyte layer; and

a unit configured to accelerate movements of the positive charge carriers, where the movements of the positive charge carriers are movements in a plane direction of the solid electrolyte layer and in a direction from the second electrode to the first electrode within the solid electrolyte layer,

wherein the unit configured to accelerate movements of the positive charge carriers is arranged on at least part of a plane of the solid electrolyte layer to be in contact with the detection-target gas, and the unit is a layer covering the solid electrolyte layer,

wherein thickness or density of the layer covering the solid electrolyte layer varies from the first electrode toward the second electrode.