A buckle device includes a buckle body that retains a tongue through which a webbing worn across an occupant is inserted; a fixing plate that is fixed to a vehicle seat and that includes a coupling webbing insertion hole; and a coupling webbing that is formed in a belt shape and that couples the buckle body and the fixing plate together. The buckle device further includes a boot that covers the coupling webbing. Moreover, the boot is provided with an engagement protrusion portion that engages with the coupling webbing insertion hole so as to suppress rattling of the boot against the fixing plate.