To provide a reliable flexible circuit board mounter by positioning a mounting board and a flexible circuit substrate in high precision, and preventing displacement after positioning.

The flexible circuit board mounter is constituted by mounting an FPC 10 on a lower substrate 2 (mounting board) of a liquid crystal panel 12. The FPC 10 and the lower substrate 2 are connected by an anisotropy conductive member such as ACP. In a mounting region 4 connecting the lower substrate 2 and the FPC 10, at least two mating portions 22 positioning the lower substrate 2 and the FPC 10 are formed. In the mating portion 22, a positioning projection 17 is formed on the front surface of a circuit pattern 15 of the FPC 10. Moreover, a positioning through-hole 18 is formed in the lower substrate 2. The positioning projection 17 and the positioning hole 18 are fitted to each other. The mounting position of the FPC 10 to the lower substrate 2 is correctly specified by fitting the positioning projection 17 and the positioning hole 18.