Gas sensor

A gas sensor comprising a sensor element which measures the concentration of a specific gas component contained in gas flowing through a flow passage provided in an internal combustion engine, a housing which accommodates the sensor element and which is inserted into the flow passage, and a base portion which is attached to the housing and which is disposed outside the flow passage, the gas sensor being characterized in that

• the base portion includes:
• a first base portion which is a portion of the base portion located on the side toward the housing;
• and
• a second base portion which is molded separately from the first base portion, which is a portion of the base portion located opposite the housing, and which has a connector portion in which a plurality of terminals which are to be connected electrically to the sensor element are disposed such that they extend in a direction intersecting an insertion direction of the sensor element.