Document and Entity Information	6 Months Ended
	Mar. 31, 2012	Apr. 25, 2012
Document and Entity Information [Abstract]
Entity Registrant Name	INSTEEL INDUSTRIES INC
Entity Central Index Key	0000764401
Document Type	10-Q
Document Period End Date	Mar. 31, 2012
Amendment Flag	false
Document Fiscal Year Focus	2012
Document Fiscal Period Focus	Q2
Current Fiscal Year End Date	--09-29
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		17,690,518