To efficiently perform shot peening to a coiled spring.

A shot peening apparatus 10 includes: a supply port to which coiled springs are supplied; a projection chamber in which shot particles are projected onto the coiled springs; a housing having an outlet from which the coiled springs onto which shot particles have been projected are discharged; a conveying device for conveying, to the outlet via the projection chamber, the coiled springs supplied to the supply port; and a projection device for projecting shot particles onto the coiled springs conveyed into the projection chamber by the conveying device. The conveying device conveys the coiled springs in a state where the axes of the coiled springs coincide with the direction in which the coiled springs are conveyed, makes a plurality of coiled springs conveyable in succession with a space therebetween in the conveying direction, and makes the space between one ends of neighboring coiled springs changeable.