The present invention provides a sample plate for laser desorption/ionization mass spectrometry, comprising: a hydrophilic thin film capable of absorbing a laser ray; and a water-repellent thin film comprising surface-hydrophobized nanoparticles and being stacked in a region other than a region to be a sample spot on a surface of the hydrophilic thin film, wherein a water contact angle of the water-repellent thin film is 120° or more.