Supported catalyst particles

A supported catalyst particle, comprising

• an oxide carrier particle and noble metal particles supported on the oxide carrier particle,
• wherein a noble metal constituting the noble metal particles is rhodium,
• the noble metal particles have a mass of 5% by mass or less based on the mass of the oxide carrier particle,
• the noble metal particles have an average particle size of 1.0 nm to 2.0 nm with a particle size standard deviation σ of 0.8 nm or less, as measured by observation with a transmission electron microscope, and
• a presence ratio of noble metal particles having a particle size of less than 1.0 nm is 5% by mass or less with respect to the total mass of the noble metal particles.