The silyl phosphine compound of the present invention is represented by the formula (1) and has an arsenic content of not more than 1 ppm. The process for producing a silyl phosphine compound of the present invention is a process comprising mixing a basic compound, a silylating agent and phosphine to obtain a solution containing a silyl phosphine compound, removing a solvent from the solution to obtain a concentrated solution of a silyl phosphine compound, and distilling the concentrated solution, wherein an arsenic content in the phosphine is adjusted to not more than 1 ppm by volume in terms of arsine. The process for producing InP quantum dots of the present invention uses, as a phosphorus source, a silyl phosphine compound represented by the formula (1) and having an arsenic content of not more than 1 ppm by mass. (For definition of R, see the specification.)