Provided is a decorative-material trimming device capable of performing a chamfering process by precisely removing an extra end of a decorative material while suppressing the tracing deviation of a guide portion with respect to a base material. This device is a decorative-material trimming device 6 which performs a chamfering process by removing an extra end S of a decorative material 9 bonded to an end surface 8a of a base material 8, including a trimming head 41 which moves along the extra end of the decorative material. The trimming head includes a drive motor 47, a rotary cutter 48 which is connected to a drive shaft 47a of the drive motor and removes the extra end of the decorative material, an attachment member 49 that is attached to the axis of the rotary cutter, and a guide portion 52 which rolls on the base material while being supported by the attachment member so as to be rotatable about the axis of the rotary cutter.