The invention provides a part inserting method and a part inserting device. Under the circumstance that a cylindrical part such as a cell is inserted in a hole of a cell module and so on, if a gap between the cylindrical part and the hole is small, the cell rubs the hole easily and thus cannot be inserted in the hole or may get damaged. The part inserting method and the part inserting device have the advantages that in a process of inserting a cylindrical part such as a cell into a holding part with a hole and under the condition of positional deviation and angle deviation between the cylindrical part and the hole of the holding part, the cylindrical part can be maintained through a fixing part which can hold and be separated from the lower end of the cylindrical part and is movable in the horizontal direction with respect to the inserting direction, and can be pulled in along the tilting of the holding part. Therefore, the cylindrical part can be inserted in the hole without damage while the position is corrected.