A latch apparatus brings a latch which is accommodated rotationally movably in a case made up of a base plate and a cover plate into engagement with a striker which enters an entrance groove in the case. A fastening member which fastens the case to a mount member so as to move relative to the striker is provided within a range defined by projecting an area which has a radius centering at the striker onto the case, the radius being equal to a distance to an outermost position of the latch which is in engagement with the striker.