A leaf spring device includes a plurality of leaf springs, in which a restricting protrusion is provided on one leaf spring, a recessed part is formed on the other leaf spring, a first side surface of the restricting protrusion and a third side surface of the recessed part face each other in a plate width direction, a second side surface of the restricting protrusion and a fourth side surface of the recessed part face each other in the plate width direction, a first inclined surface is formed on one of the first and third side surfaces to be further away from the other thereof from a central portion toward a first direction, and a second inclined surface is formed on one of the second and fourth side surfaces to be further away from the other thereof from the central portion toward a second direction.