The present disclosure provides a device for reclining a seatback for a vehicle, which may allow a separate actuator to be driven by a switching signal of a lever switch when a user operates the lever switch with only a small force such that a cable connected to a latch for locking or unlocking a recliner may be pulled in an unlock direction of the recliner, thereby implementing the reclining operation for adjusting an angle of the seatback in a semiautomatic manner.