A robot apparatus includes a clamp mechanism; a transport mechanism; and a control unit. The clamp mechanism includes a first finger that has a first support surface and a housing portion and a second finger. The first support surface supports an aligned wire group that includes a plurality of wires, the housing portion includes a guide wall that is connected to the first support surface and regulates an amount of movement of the band member in a width direction. The second finger has a second support surface facing the first support surface and a facing portion being connected to the second support surface and facing the housing portion. The transport mechanism is capable of moving the clamp mechanism. The control unit controls a grip force of the clamp mechanism and a direction of movement of the clamp mechanism by the transport mechanism.