To reduce cost and to enhance reliability by linking a rotatable rod member centering around a fixed flange, rotatably linking a rocking core of a radar antenna with an end part on the opposite side of the side of the fixed flange of the rod member, coupling the side of another end of an axis part on the antenna side of a link with a center of a motor and rocking the antenna by rotation of the motor.

When a motor 6 is rotated, a disk 8 installed on a shaft 7 of the motor 6 is also rotated. A working pin 9 is fixed at a position which is eccentric with certain distance from the rotational center of the motor 6 on the disk 8. A hinge part 11 with an open cylindrical bole 10 is constituted at an outer edge part of the antenna 5 so that it is rotated with the working pin 9. The rocking core 12 of the antenna 5 is provided at a center part of the antenna 5. The rocking core 12 is constituted of a hinge part 13 with an open hole, the rocking core 12 is a hole and exists on the top and bottom sides of the antenna 5. Each hole of the rocking core 12 of the antenna 5 is engaged with a pin so that it is rotated with a hole on one end of a crank rod 15.