PURPOSE: To improve the reliability of the connection of connection terminals formed on a flexible substrate and terminals on another substrate.

CONSTITUTION: Connection terminals 15a and 15b are formed on the substrate 13 of an electroluminescent display element so that their both ends are the connection terminals 15b. Also, connection terminals l6a and l6b corresponding to the connection terminals 15a and 15b formed on the substrate 13 are formed on a flexible substrate 14. The connection terminals 15b and 16b are formed in the manner of being larger in terminal width W2 than the connection terminals 15a and 16a, and when the connection terminals 15a, 15b and 16a, 16b are connected with each other, a connection area and bond strength increase as the terminal width grows larger because the connection terminals 15b and 16b with larger terminal width are formed at both ends.