To provide a nucleic acid microarray which can be used to detect the expression of a gene or the like without not depending to the manual skill of an experimenter, and to provide a method for detecting a nucleic acid therewith.

This nucleic acid microarray containing washing level meter probes, and the method for detecting the nucleic acid is characterized by comprising the following processes (1) to (4): (1) a process for preparing a sample nucleic acid, (2) a process for bringing the sample into contact with the microarray to perform a hybridization reaction, (3) a process for stepwisely washing the microarray after the hybridization reaction from the weak side of washing degree to the strong side, and (4) a process for detecting the hybrid formed in (4).