A rotary reciprocating drive actuator comprising: a base portion; a movable magnet fixed to a shaft portion to which a movable object is connected; and a drive unit having a core body and a coil body for generating a magnetic flux in the core body when current is supplied, and driving the movable magnet in a rotary reciprocating manner by an electromagnetic interaction between the magnetic flux generated from the core body and the movable magnet, wherein the movable magnet is formed in a ring shape, and is configured by alternately magnetizing an even number of magnetic poles (161a, 161b) forming an S - pole and an N - pole at an outer periphery of the shaft portion; a number of magnetic poles (211a, 212a) of the core body and a number of magnetic poles (161a, 161b) of the movable magnet are equal to each other; an even number of magnetic poles (211a, 212a) of the core body is respectively arranged to face the movable magnet with an air gap therebetween on the outer peripheral side of the shaft portion; the drive unit is provided with a magnet position holding portion which is a magnetic material provided to face the movable magnet and magnetically attracts the movable magnet to a reference position; a pair of wall portions (111a, 111b) is erected on the base portion to rotatably support the shaft portion via a bearing, and the movable object is disposed between the pair of wall portions (111a, 111b); the drive unit is attached to one wall portion of the pair of wall portions (111a, 111b), and an angle sensor portion for detecting the rotation angle of the shaft portion is attached to the other wall portion of the pair of wall portions (111a, 111b); and the angle sensor portion includes an optical sensor and an encoder disk that is mounted by fastening to the shaft portion via a mounting member to rotate integrally with the movable magnet and the movable object, and a rotational position of the encoder disk is detected by the optical sensor. a base portion; a movable magnet fixed to a shaft portion to which a movable object is connected; and a drive unit having a core body and a coil body for generating a magnetic flux in the core body when current is supplied, and driving the movable magnet in a rotary reciprocating manner by an electromagnetic interaction between the magnetic flux generated from the core body and the movable magnet, wherein the movable magnet is formed in a ring shape, and is configured by alternately magnetizing an even number of magnetic poles (161a, 161b) forming an S - pole and an N - pole at an outer periphery of the shaft portion; a number of magnetic poles (211a, 212a) of the core body and a number of magnetic poles (161a, 161b) of the movable magnet are equal to each other; an even number of magnetic poles (211a, 212a) of the core body is respectively arranged to face the movable magnet with an air gap therebetween on the outer peripheral side of the shaft portion; the drive unit is provided with a magnet position holding portion which is a magnetic material provided to face the movable magnet and magnetically attracts the movable magnet to a reference position; a pair of wall portions (111a, 111b) is erected on the base portion to rotatably support the shaft portion via a bearing, and the movable object is disposed between the pair of wall portions (111a, 111b); the drive unit is attached to one wall portion of the pair of wall portions (111a, 111b), and an angle sensor portion for detecting the rotation angle of the shaft portion is attached to the other wall portion of the pair of wall portions (111a, 111b); and the angle sensor portion includes an optical sensor and an encoder disk that is mounted by fastening to the shaft portion via a mounting member to rotate integrally with the movable magnet and the movable object, and a rotational position of the encoder disk is detected by the optical sensor.