To provide a clothes forming device and a clothes forming method capable of beautifully forming without pressing a collar of clothes.

A clothes forming device 1 of this invention includes: a forming part 10 having a curved surface 11 corresponding to a shape of a collar of clothes; a heating part for heating the forming part 10; a holding part 20 for holding both ends of the collar of the clothes along the curved surface 11 of the forming part 10; an expansion part 30 for expanding the collar of the clothes in a state where the collar of the clothes is being held by the holding part 20; and a rocking part 40 for rocking the collar of the clothes in a state where the collar of the clothes is being expanded by the expansion part 30.