PURPOSE: To prevent exactly a lining from stripping off from a pipe, by inserting a porous pipe to which a porous plate is wound cylindrically, into a pipe, shifting both end edges of its circumferential direction in the axial direction, making both end edges contact closely, and covering said pipe with mold forming.

CONSTITUTION: A porous plate 19 is formed like a parallelogram, and is wound cylindrically so that it can be inserted into a pipe 11 used for an electromagnetic flowmeter, by which a porous pipe 15a is formed. In this case, a slit 18 is formed between end edges 16, 17 in the circumferential direction of the porous pipe 15a. This porous pipe 15a is inserted into the pipe 11, and thereafter, the end edge 16 or 18 is shifted relatively in the X direction or the Y direction, both end edges 16, 17 are made to contact closely with each other, and a porous pipe 15 is formed. Subsequently, this porous pipe 15 is covered with mold forming, and a lining 13 is manufactured. In this way, it is possible to obtain an electromagnetic flowmeter which causes no measuring error at the time of measurement of a flow rate.