PROBLEM TO BE SOLVED: To provide a thrombosis preventing device which is configured to be smaller and easily mounted, and assists the lower limb motion of a passenger sitting on a seat in an airplane of a long distance route or the like or a patient under surgery or after surgery, and in which the pump function by a self physiological muscle is used, and the blood flow of a deep part vein is made to increase, and the thrombus is prevented.SOLUTION: The thrombosis preventing device includes: a body 1 which has a body support section 2 an oscillating body 4 which is rotatably supported by a rotary shaft 3 to the body support section 2 and is equipped with a sole support plate 6 and a rocking mechanism 5 which is prepared at the body 1, and in which the one end thereof is connected with the oscillating body 4, and which makes the sole support plate 6 rock. When the toe is laid on the sole support plate 6, the oscillating body 4 is made to rock, thereby the dorsiflexion and extension motion can be carried out centering the ankle of a foot joint.COPYRIGHT: (C)2012,JPO&INPIT【課題】より小型で容易に装着可能な構成にして、長距離路線の飛行機内等の座席に座っている乗客とか、手術中或いは手術後の患者の下肢運動を補助し、生理的な自己の筋肉によるポンプ機能を用いて、深部静脈の血流を増加させ、血栓を予防する。【解決手段】本発明は、本体支持部2を有する本体部1と、本体支持部2に対して回転可能に回転軸3により支持され、かつ足裏支持板6を備えた揺動体4と、本体部1に備えられ、かつ一端が揺動体4に連結されて、足裏支持板6を揺動させる揺動機構5とを備える。足裏支持板6上に足先を載置した際には、揺動体4を揺動させることにより、足首の踝を中心に足関節を背屈及び伸展運動させることができる。【選択図】 図1