A method for crimping a terminal to an aluminum electric wire comprising: preparing a terminal having an electric connecting portion which is configured to be connected with a mating terminal at a front end side thereof, and a conductor crimping portion which is configured to be crimped to a conductor of an electric wire configured to be connected therewith by being bent inward to be crimped at a rear end side thereof, preparing an aluminum electric wire having a conductor made of aluminum or an aluminum alloy as the electric wire configured to be connected with the conductor crimping portion; and crimping the conductor crimping portion to the conductor of the aluminum electric wire by bending the conductor crimping portion inwards so as to embrace the conductor in a state that the conductor of the aluminum electric wire is inserted into an interior of the conductor crimping portion of the crimp terminal, wherein at least an inner surface of the conductor crimping portion is plated with a metal whose hardness is lower than a hardness of a metal of a terminal base material, and a thickness of the metal applied to plate the inner surface is set to be in a range from 2.1 μm to 5.0 μm, characterized in that a thickness of the metal applied to plate the inner surface of the conductor crimping portion is thicker than a thickness of the metal applied to plate an inner surface of the electric connection portion; the aluminum electric wire has an insulated sheathing configured to be crimped with a sheathing crimping portion of the terminal; and the electric connecting portion, the conductor crimping portion and the sheathing crimping portion are configured so as to include a common bottom plate part. preparing a terminal having an electric connecting portion which is configured to be connected with a mating terminal at a front end side thereof, and a conductor crimping portion which is configured to be crimped to a conductor of an electric wire configured to be connected therewith by being bent inward to be crimped at a rear end side thereof, preparing an aluminum electric wire having a conductor made of aluminum or an aluminum alloy as the electric wire configured to be connected with the conductor crimping portion; and crimping the conductor crimping portion to the conductor of the aluminum electric wire by bending the conductor crimping portion inwards so as to embrace the conductor in a state that the conductor of the aluminum electric wire is inserted into an interior of the conductor crimping portion of the crimp terminal, wherein at least an inner surface of the conductor crimping portion is plated with a metal whose hardness is lower than a hardness of a metal of a terminal base material, and a thickness of the metal applied to plate the inner surface is set to be in a range from 2.1 μm to 5.0 μm, characterized in that a thickness of the metal applied to plate the inner surface of the conductor crimping portion is thicker than a thickness of the metal applied to plate an inner surface of the electric connection portion; the aluminum electric wire has an insulated sheathing configured to be crimped with a sheathing crimping portion of the terminal; and the electric connecting portion, the conductor crimping portion and the sheathing crimping portion are configured so as to include a common bottom plate part.