Document and Entity Information - shares	9 Months Ended
	Mar. 31, 2019	May 07, 2019
Document and Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q3
Entity Registrant Name	NAPCO SECURITY TECHNOLOGIES, INC
Entity Central Index Key	0000069633
Current Fiscal Year End Date	--06-30
Entity Filer Category	Accelerated Filer
Trading Symbol	NSSC
Entity Common Stock, Shares Outstanding		18,474,879
Entity Emerging Growth Company	false
Entity Small Business	true