To easily and surely fit both bearing seat bodies to both side faces of a door body.

A bearing seat fitting device for a door look is provided with a bearing seat body 12 in one side which has a plurality of fitting holes and is brought in contact with a side face in the thickness wire direction of the door body and a bearing seat body 27 in the other side being in contact with the other side face in the thickness direction of the door body. A plurality of engaging projecting bodies 13, 18 which are engaged with a plurality of fitting holes of the door respectively and have shaft insertion holes 14, 19 are provided in either one of the bearing seat body 12 out of the bearing seat body 12 in one side and the bearing seat body 27 in the other side, and a plurality of engaging shaft 28, 31 which are engaged with shaft insertion holes 14, 19 of a plurality of the engaging projection bodies 13, 18 of the one bearing seat body 12 respectively are provided in the other bearing seat body 27. A plurality of the engaging projection bodies 13, 18 have axial ridges 15, 20 in their outside parts. A plurality of the engaging shaft 28, 31 have axial projection line 29, 32 in their outside parts. The both bearing seat bodies 12, 27 have axial insertion holes 21, 33 for inserting a handle shaft 55 thereinto.