To provide a pivoting angle adjustment mechanism in which a manual operation for adjustment in multistage for pivoting angles of two members pivoted to enable a relative pivoting to be carried out can be easily performed.SOLUTION: A constitution of a pivoting angle adjustment mechanism is provided in such a way that it includes a support shaft 40 having a pivoting shaft part 40a for supporting the first member 1 and the second member 2 in a relative rotatable manner and its head part 40b is biased in a direction moving away from the first member； several small holes 11 passed through the first member along an arc concentric with the pivoting shaft at the first member； an appearing or disappearing head 36 inserted into a bottomed hole part 20 at the second member and biased in a protruding direction； and several pins 45 each of which is inserted into the small holes when the head part is depressed and a locus of the appearing or disappearing head when the second member is pivoted overlaps on a circular arc having several small holes.SELECTED DRAWING: Figure 1【課題】相対的な回動可能に軸支されている二つの部材の回動角度を、手動で多段階に調整する操作を簡単に行うことができる回動角度調整機構を提供する。【解決手段】回動角度調整機構の構成を、第一部材１及び第二部材２を相対的な回動可能に軸支している回動軸部４０ａを有し、その頭部４０ｂが第一部材から離れる方向に付勢されている支軸４０と、第一部材において回動軸部と同心の円弧に沿って貫設されている複数の小孔部１１と、第二部材において有底孔部２０に挿入され、突出する方向に付勢されている出没ヘッド３６と、頭部の裏面から、複数の小孔部と同一の角度間隔、同一の数、及び回動軸部から同一の距離で小孔部に向かって突出しており、頭部が押圧されたときに小孔部にそれぞれ挿入される複数のピン４５とを具備し、第二部材が回動する際の出没ヘッドの軌跡が、複数の小孔部が設けられている円弧と重なっている構成とする。【選択図】図１
