PURPOSE: To provide a shot peening method for small tube of a steam generator for which safety, reliability and efficiency are improved and a device therefor.

CONSTITUTION: A load tank 61 forms an air lock for recirculating shot recovered and cleaned by a vacuum system 39 to a pressurized peening tank 57, feeds recirculating shot to a feed valve 53 for mixing with compressed air flow and generates shot stream. Pressure applying to shot within the peening tank 57 and pressure of compressed air supplied to the feed valve 53 are independently regulated each other and concentration of shot in shot stream is adjusted. A purge line 99 recirculates shot and debris purged from the feed valve 53 to a shot cleaning device 87 on the vacuum side.