A surface-assisted laser desorption/ionization method according to an aspect includes: a first process of preparing a sample support (2) having a substrate (21) in which a plurality of through-holes (S) passing from one surface (21a) thereof to the other surface (21b) thereof are provided and a conductive layer (23) that covers at least the one surface (21a); a second process of placing a sample (10) on a sample stage (1) and arranging the sample support (2) on the sample (10) such that the other surface (21b) faces the sample (10); and a third process of applying a laser beam (L) to the one surface (21a) and ionizing the sample (10) moved from the other surface (21b) side to the one surface (21a) side via the through-holes (S) due to a capillary phenomenon.