PURPOSE: To improve the productionability of an automatic assembler for snapring, by enabling automatic assembling of snapring to be fitted in the outercircumferential groove of sleeve to hold a springboard under resiliently deformed state.

CONSTITUTION: Parts to be assembled are comprised of a hab sleeve 39 formed with an outercircumferential groove 43 and a springboard 42 fitted over said sleeve 39. Automatic assembler for fitting a snapring (a) in the outercircumferential groove 43 of said parts is comprised of a guide body 31 for fitting snapring (a) over the outercircumference, carrying mechanism 2 for carrying saig guide body 31 to fit the lower end section in the hab sleeve 39 and a tubular press body to be fitted over the guide body 31. Furthermore, a press mechanism for lowering the press body while inserting the guide body 31 to press a snapring (a) held on the guide body 31 and fit in the outercircumferential groove 43 is provided.