PURPOSE: To obtain a copper alloy for flexible tube excellent in corrosion resistance, bendability, and workability, by providing a copper alloy consisting of specific amounts of Si and Al and the balance Cu with inevitable impurities.

CONSTITUTION: The copper alloy has a composition consisting of, by weight, 1.0W3.5% Si, 0.01W0.5% Al, and the balance Cu with impurities, or has the one consisting of the same amount of Si and Al and the balance Cu with inevitable impurities and further containing, selectively ≤0.5% of one element among Fe, Ni, Zn, Sn, etc., or ≤1.0%, in total, of ≥2 elements among the above. This copper alloy is subjected to hot and cold rollings to undergo formation into a tube of the prescribed dimensions and then to rapid heating at a rate of ≥80°C/sec, so that soft material can be manufactured. In this way, the copper alloy for flexible tube excellent in corrosion resistance, bendability, and workability can be obtained.