The invention provides a recombinant vector, which includes repeats of Amyloid β 1-42 (Aβ1-42) gene, an immunoglobulin Fc gene, a spacer sequence and interleukin-4 gene in this order, the repeats of the Aβ1-42 gene contain spacer sequences between the individual Aβ1-42 genes. The invention also provides a DNA vaccine for Alzheimer's disease, which includes the recombinant vector.