PROBLEM TO BE SOLVED: To provide a cabin storage type auxiliary step optimal to a vehicle where riding in or out is performed at an entrance separately to the right and left side thereof (in a vehicular forward-backward direction) like in a three-row seat vehicle such as a mini-van.SOLUTION: There is provided a step board 1 capable of freely reciprocating between a storage position X on a vehicle step S existing in a cabin and an extended position Y at a front lower part of the vehicle step S. In the vicinity of the center of the step board 1, step board support mechanism parts 2, 13, and 14 are provided between the step board 1 and the vehicle step S side, for horizontally disposing the step board 1 at the storage position X and at the extended position Y, and reciprocating the same on a constant path. The step board 1 is vertically provided with support poles 2 in the vicinity of the center, and arms 13 are pivotally connected between the support poles 2 and the vehicle step S side, for suspending the support poles 2 at the extended position Y. At a proper position of the arms 13, a bent part of a bell crank 15 is pivoted, and between one end of the bell crank 15 and the support poles 2, and between the other end of the bell crank 15 and the vehicle step S side, links 16 and 17 are respectively pivotally connected.SELECTED DRAWING: Figure 1【課題】ミニバン等の３列シート車の様に、乗降口でその左右（車両の前後方向）に分かれて乗降する車両に最適な車室内格納式補助ステップを提供する。【解決手段】車室内に既設された車両ステップＳ上の格納位置Ｘと、車両ステップＳ前方下部の張出位置Ｙとの間を往復動自在に設けた踏板１であって、該踏板１の中央部近傍には、踏板１を格納位置Ｘと張出位置Ｙで水平に配置させ、且つ、一定の軌道上を往復動させる踏板支持機構部２、13、14を車両ステップＳ側との間に設け、踏板１は、中央部近傍に支柱２を垂直立設し、該支柱２と車両ステップＳ側との間に上記張出位置Ｙで支柱２を懸垂するアーム13を枢着連結し、アーム13の適所にべルクランク15の屈曲部を枢着し、該べルクランク15の一端と支柱２との間、及びべルクランク15の他端と車両ステップＳ側との間の夫々にリンク16、17を枢着連結する。【選択図】図１
