A method of detecting a target nucleic acid sequence comprising providing a stem-and-loop structured nucleic acid for measurement wherein the nucleic acid comprises complementary sequence portions located at both terminals and a target sequence portion therebetween as well as a double-stranded portion formed by hybridization of the complementary sequence portions located at both terminals and a remaining looped single-stranded portion, providing a probe nucleic acid having a sequence complementary to the target sequence portion wherein one end of the probe nucleic acid being immobilized to a solid substrate surface, reacting the nucleic acid for measurement with the probe nucleic acid to specifically hybridize the target sequence portion of the nucleic acid for measurement to the probe nucleic acid, and detecting presence or absence of the nucleic acid for measurement hybridized to the probe nucleic acid.