According to the present invention, a grain-oriented electrical steel sheet for iron cores exhibiting excellent transformer iron loss properties in an excitation range from 1.5 T to 1.9 T is provided, in which a residual stress of 150 MPa or more is formed near strain regions, each extending 300 μm or less in the rolling direction and 42 μm or more in the sheet thickness direction, and the strain regions are formed periodically at intervals of 2 mm to 10 mm in the rolling direction, with reduced energy loss in transformers in operation.