To provide a sliding door opening/closing device for a vehicle, which achieves facilitation of manufacture, improvement in operability and safety, and reducing a noise by employing a constitution wherein a sufficient opening/closing driving force to right and left sliding doors is applied and a force required for the shutting/opening of a latch lock is reduced despite the simplicity of the constitution.

A lock device 100, on which locking portions 402 and 502 abut from both sides, rotates a cylindrical permanent magnet 108 to form a magnetic circuit for locking, and fixes the locking portions 402 and 502 by the magnetic force of the magnetic circuit for locking. The rotational motion of the cylindrical permanent magnet 108 is converted to the descending motion of the latch lock 113. Furthermore, the descended latch lock 113 restrains the locking portions 402 and 502 to the lock device 100.