A binding device includes a receptacle, an aligner, a moving mechanism, first and second binders, and a guide. The aligner aligns a bundle of recording media in a width direction thereof on the receptacle. The moving mechanism moves the aligner in the width direction. A maximum thickness of the bundle of recording media boundable in the second binder is smaller than that in the first binder. The guide is movable conforming to the maximum thickness of the bundle of recording media boundable in the first binder, and conforming to that in the second binder, to guide and direct the bundle of recording media to a receiving portion of the first binder when the first binder binds the bundle of recording media, and to a receiving portion of the second binder when the second binder binds the bundle of recording media, respectively. The guide is movable in conjunction with the aligner.