Sensor element and gas sensor

A sensor element for detecting a concentration of a specific gas in a measurement-object gas, the sensor element comprising:

• an element body having an oxygen-ion-conductive solid electrolyte layer, and having a measurement-object gas flow section inside that introduces the measurement-object gas from a gas inlet and causes the measurement-object gas to flow in a first direction;
• a pump cell including an inner electrode provided in an internal cavity of the measurement-object gas flow section and an outer electrode provided on an outer surface of the element body, and
• a diffusion control section that is located upstream of the internal cavity in the measurement-object gas flow section and that provides the measurement-object gas introduced from the gas inlet with diffusion resistance,
• wherein the diffusion control section includes a porous body and a space portion that are provided in at least a part of the diffusion control section in the first direction, the porous body is provided so as to occupy a part of a cross-section of the diffusion control section perpendicular to the first direction and allows the measurement-object gas to pass therethrough, and the space portion includes a part of the cross-section not occupied by the porous body and allows the measurement-object gas to pass therethrough.