Electrolytic copper plating liquid and the electrolytic copper plating method

Copper electroplating liquid which does not use formaldehyde, which is harmful to the environment, and which exhibits excellent via filling ability is offered. The copper electroplating liquid of this invention includes the compound that has the structure of -X-S-Y- where X and Y are each an atom selected from the group of hydrogen atoms, carbon atoms, sulfur atoms, nitrogen atoms and oxygen atoms, and X and Y can be the same only when they are carbon atoms, and a specific urea derivative. When the copper electroplating liquid is used, deterioration of the appearance will not occur and a good filled via can be formed.