Latch device for vehicle seat

A latch assembly 5 includes a base plate 10 having a striker groove 11, a latch 12 provided in the base plate 10 and having a striker engaging groove 16, and a ratchet 20 for regulating rotation of the latch 12 in unlatch direction. A looseness eliminating lever 30 is attached to the latch 12 by means of a pin 31 moving around a latch shaft 13, one end of the looseness eliminating lever 30 is provided with a latch holding face 34 and an unlatch face 33 to contact with a post 32 provided at a specified position, the other end of the lever 30 is provided with a spring 14 for biasing the guide face 34 or the sliding face 33 to be always in contact with the post 32, and an apex 35 as a dead center is formed between the guide face 34 and the sliding face 33. The guide face 34 is formed in an arc-shaped inclined surface so as to be remoter from the pin 31 from a start end to a terminal end.