Provided is a substrate for mass spectrometry, which enables a detection of a high molecular weight compound to be conducted at a high sensitivity, and can avoid the fragmentation so that there is substantially no obstacle to the analysis of a low molecular weight region. The substrate is a substrate for mass spectrometry for use in laser desorption/ionization mass spectrometry, containing a metal and having a porous structure on a surface thereof, wherein at least one functional group selected from the group consisting of a carboxyl group, a sulfonic group and an ammonium chloride group is covalently bonded to the surface of the substrate.