A laundry treatment apparatus includes a casing; an outer tub; a supporting member coupling the outer tub to the casing; and at least one horizontal vibration buffering device connecting the supporting member with a side surface of the casing. The horizontal vibration buffering device includes a casing connecting part coupled to the casing; a supporting member connecting part coupled to the supporting member, and a damper. The supporting member connecting part has a displacement relative the casing connecting part as the outer tub vibrates. The damper provides an attenuation force corresponding to the displacement of the supporting member connecting part relative the casing connecting part.