Document And Entity Information - shares	3 Months Ended
	Sep. 30, 2018	Nov. 08, 2018
Document Information [Line Items]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2018
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q1
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		18,574,845
Entity Emerging Growth Company	false
Entity Small Business	true