After melted enamel coating is discharged, a fusion process of electrical wire-to-wire connection is carried out inside a crimping connector. In the conductor connection method based on the fusion process, a plurality of enamel-coated conductor wires are inserted in the crimping connector prior to the start of the fusion process. Further, a temporary crimping process that provides the crimping connector a temporary crimping by mechanical pressurizing means is also performed. Addition of force at both end parts or either end part of the cross-section orthogonal to the axis of the above crimping connector may cause expansion, which needs to be suppressed with external force. At the same time, the cross-sectional areas corresponding to both end parts or either end part should preferably be as small as possible. The temporary crimping is applied to the crimping connector for this purpose.