A sensor element comprising: a multilayer body formed by stacking a plurality of solid electrolyte layers each having oxygen ion conductivity, and including a measurement-object gas flowing portion (10-13, 20, 30, 40, 60, 61) that is formed in the multilayer body, and that allows measurement object gas to be introduced from an outside therethrough; a measurement electrode disposed in a measurement electrode mounting space that is a part of the measurement-object gas flowing portion; an outer pump electrode disposed on an outer surface of the multilayer body; a connector electrode for the outer pump electrode, the connector electrode being disposed on the outer surface of the multilayer body; a lead portion for the outer pump electrode, the lead portion being disposed on the outer surface of the multilayer body and providing electrical conduction between the outer pump electrode and the connector electrode for the outer pump electrode; a porous protective layer disposed on the outer surface of the multilayer body and covering at least the outer pump electrode; and a blocking portion including an outer blocking layer that is disposed between the lead portion for the outer pump electrode and the outer surface of the multilayer body to provide insulation therebetween, that is disposed between the connector electrode for the outer pump electrode and the outer surface of the multilayer body to provide insulation therebetween, that is disposed to cover at least a part of a closest region where the outer pump electrode is not disposed and a distance up to the measurement electrode mounting space is minimal among the outer surface, and that does not have conductivity for one or more among various types of substances containing oxygen. a multilayer body formed by stacking a plurality of solid electrolyte layers each having oxygen ion conductivity, and including a measurement-object gas flowing portion (10-13, 20, 30, 40, 60, 61) that is formed in the multilayer body, and that allows measurement object gas to be introduced from an outside therethrough; a measurement electrode disposed in a measurement electrode mounting space that is a part of the measurement-object gas flowing portion; an outer pump electrode disposed on an outer surface of the multilayer body; a connector electrode for the outer pump electrode, the connector electrode being disposed on the outer surface of the multilayer body; a lead portion for the outer pump electrode, the lead portion being disposed on the outer surface of the multilayer body and providing electrical conduction between the outer pump electrode and the connector electrode for the outer pump electrode; a porous protective layer disposed on the outer surface of the multilayer body and covering at least the outer pump electrode; and a blocking portion including an outer blocking layer that is disposed between the lead portion for the outer pump electrode and the outer surface of the multilayer body to provide insulation therebetween, that is disposed between the connector electrode for the outer pump electrode and the outer surface of the multilayer body to provide insulation therebetween, that is disposed to cover at least a part of a closest region where the outer pump electrode is not disposed and a distance up to the measurement electrode mounting space is minimal among the outer surface, and