A method for selecting a silicon single crystal substrate for controlling carrier recombination lifetime, comprising: a preparation step of preparing a silicon single crystal substrate as a candidate for the silicon single crystal substrate by fabrication from a silicon single crystal ingot; a particle beam irradiation step of irradiating the prepared silicon single crystal substrate with a particle beam; a recovery heat treatment step of heat-treating the silicon single crystal substrate after the particle beam irradiation step; a measurement step of injecting excess carriers into the silicon single crystal substrate after the recovery heat treatment step and measuring an excess carrier decay curve, which is a decay curve of an excess carrier concentration in relation to time elapsed after injecting the excess carriers, wherein a microwave photoconductive decay method is used as a method for measuring the decay curve; a judgement step of obtaining, in the measured excess carrier decay curve, a time LT until the excess carrier concentration decays to 1/e times the excess carrier concentration at the time of injection and a time t Tail until the excess carrier concentration decays to X% (1≤X≤10) of the excess carrier concentration at the time of injection, and then calculating Δt Tail, which is a difference between the time t Tail and an ideal decay time [-LT×ln(X/100)] until the excess carrier concentration decays to X% of the excess carrier concentration at the time of injection using the following equation 1, and judging the silicon single crystal substrate as acceptable when a value of the time Δt Tail is a predetermined judgement value or less; and a selection step of selecting a silicon single crystal substrate fabricated from the same silicon single crystal ingot as the silicon single crystal ingot from which the silicon single crystal substrate judged as acceptable in the judgement was fabricated as the silicon single crystal substrate for controlling carrier recombination lifetime. Δt Tail X = t Tail X − − LT × ln X / 100 a preparation step of preparing a silicon single crystal substrate as a candidate for the silicon single crystal substrate by fabrication from a silicon single crystal ingot; a particle beam irradiation step of irradiating the prepared silicon single crystal substrate with a particle beam; a recovery heat treatment step of heat-treating the silicon single crystal substrate after the particle beam irradiation step; a measurement step of injecting excess carriers into the silicon single crystal substrate after the recovery heat treatment step and measuring an excess carrier decay curve, which is a decay curve of an excess carrier concentration in relation to time elapsed after injecting the excess carriers, wherein a microwave photoconductive decay method is used as a method for measuring the decay curve; a judgement step of obtaining, in the measured excess carrier decay curve, a time LT until the excess carrier concentration decays to 1/e times the excess carrier concentration at the time of injection and a time t Tail until the excess carrier concentration decays to X% (1≤X≤10) of the excess carrier concentration at the time of injection, and then calculating Δt Tail, which is a difference between the time t Tail and an ideal decay time [-LT×ln(X/100)] until the excess carrier concentration decays to X% of the excess carrier concentration at the time of injection using the following equation 1, and judging the silicon single crystal substrate as acceptable when a value of the time Δt Tail is a predetermined judgement value or less; and a selection step of selecting a silicon single crystal substrate fabricated from the same silicon single crystal ingot as the silicon single crystal ingot from which the silicon single crystal substrate judged as acceptable in the judgement was fabricated as the silicon single crystal substrate for controlling carrier recombination lifetime. Δt Tail X = t Tail X − − LT × ln X / 100