To provide a water/oil repellent layer-provided substrate having a water/oil repellent layer excellent in abrasion resistance, a deposition material and a method for producing a water/oil repellent layer-provided substrate. The water/oil repellent layer-provided substrate comprises a substrate, an undercoat layer and a water/oil repellent layer in this order. The water/oil repellent layer comprises a condensate of a fluorinated compound having a reactive silyl group, the undercoat layer contains an oxide contains silicon and at least one element of boron and phosphorus, and a ratio of the total molar concentration of boron and phosphorus in the undercoat layer to the molar concentration of silicon in the undercoat layer is from 0.003 to 9.