A knife holder for a lawn mower includes a pedestal, a fixation member, a motor, a cutter and a position-limiting assembly. The pedestal defines an axial direction. The fixation member is disposed on the pedestal and has a first annular wall. A first bearing is received in the first annular wall. The motor is disposed on the pedestal and includes a base, a rotator and shaft. The base is disposed on the pedestal and has a second annular wall. Two second bearings are received in the second annular wall. The shaft and the rotator are in a rotation-connecting relationship and the shaft is disposed through the two second bearings and the first bearing.本發明關於一種割草機刀座頭，其包括一座體、一固定片、一馬達、一刀具及一限位組件。該座體定義一軸向。該固定片設於該座體並具有一第一環壁，該第一環壁內容設有一第一軸承。該馬達設於該座體，包括一基座、一轉子及一轉軸，該基座設於該座體並具有一第二環壁，該第二環壁內容設有二第二軸承，該轉軸與該轉子連結同動並穿設於該二第二軸承及該第一軸承。
