A servo accelerometer has a pair of housings having a tubular part, one end opened and the other end closed with a closing part. A frame that supports a pendulum is held between the housings. A permanent magnet is attached to each of the closing parts with a bottom pole piece interposed therebetween. Coils arranged in annular magnetic gaps are attached to the pendulum. The closing part has a recess, and the bottom pole piece is disposed in the recess. The outer circumference of the bottom pole piece faces the inner circumference of the recess with a predetermined gap interposed therebetween.