Sensor provided with plurality of circuit boards

A sensor, comprising:

• a base member, on which a first placement surface and a second placement surface parallel to the first placement surface are formed;
• a first rigid substrate, fixed to the first placement surface;
• and
• a second rigid substrate, fixed to the second placement surface,
• wherein an electronic component used for sensing is mounted to straddle the first rigid substrate and the second rigid substrate,
• the base member comprises a first projection part, a second projection part, and a third projection part, being columnar and projecting from the first placement surface,
• the second placement surfaces are formed at tip ends of the first projection part, the second projection part, and the third projection part,
• the first projection part comprises a fourth pin projecting from the second placement surface to be inserted through the second rigid substrate,
• the second projection part comprises a fifth pin projecting from the second placement surface to be inserted through the second rigid substrate,
• three ribs are formed on a peripheral surface of the fourth pin, the three ribs being disposed so that positions viewed from a center of the fourth pin respectively form angles less than 180 degrees, and
• two ribs are formed on a peripheral surface of the fifth pin, and the two ribs project along a fourth line perpendicular to a third line connecting the fourth pin and the fifth pin.