A carrier device includes an attachment having a base member, a unidirectional bearing member engaged in the base member, a mounting seat having a coupler, and a shaft device attached to the coupler and engaged with the unidirectional bearing member for rotatably attaching the coupler and the mounting seat to the base member of the attachment, and the unidirectional bearing member is arranged to allow the shaft device and the coupler and the mounting seat to be rotated only upwardly relative to the base member. The coupler includes a space for forming two ears and for receiving the base member. The ears each include a recess communicating with the space of the coupler for engaging with the shaft device.