Abstract: A cleavable signal element applicable to quantitative and qualitative assay devices, using a cleavable technique specifically responsive to a complementary double strand or single strand of nucleic acids, and a nucleic acid hybridization assay method and device using the cleavable signal element are provided. Using the cleavable technique responsive to the complementary double strand or single strand of nucleic acids, detection sensitivity to a target nucleic acid can be increased, and diagnosis and detection reliability can be improved twice through in-situ determinations. Through simultaneous single nucleotide polymorphism (SNP) detection and expression profile determination, more accurate diagnosis for many diseases can be achieved. The assay device can be easily modified to be suitable for detection with general laser-based detection systems such as CD-ROM readers.