To provide a connection structure that can be crimped and connected in a desired crimping shape to the electric wire tip portion of an insulated wire without causing the deformation into an unintended crimping shape of the crimping portion of a crimp terminal. When crimping a conductor crimping portion (30a) of crimp terminal (10) to an electric wire tip portion (200a) of insulated wire (200), outer peripheral contact portions (613, 613) of a lower blade (61) of a crimping device (60A) and an outer peripheral contact portion (623) of an upper blade (62) are point-contacted to an outer periphery of a conductor crimping portion (30a) in a perpendicular cross section in a direction perpendicular to a longitudinal direction X and to a crimping direction Z so as to be left-right symmetrical with respect to a reference plane formed by the longitudinal direction (x) and the crimping direction (Z).