The present disclosure is a spherical strontium titanate fine particulate powder with a primary particle having an average primary particle size equal to or less than 50 nm, the spherical strontium titanate fine particulate powder having a ratio between the average primary particle size and a BET-converted particle size ranging from 0.85 to 1.25, the BET-converted particle size derived from a BET specific surface area by using the expression 6000/(BET x 5.13).