Document And Entity Information - shares	3 Months Ended
	Dec. 26, 2020	Jan. 19, 2021
Document Information [Line Items]
Entity Central Index Key	0000785956
Entity Registrant Name	J&J SNACK FOODS CORP
Amendment Flag	false
Current Fiscal Year End Date	--09-25
Document Fiscal Period Focus	Q1
Document Fiscal Year Focus	2021
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Dec. 26, 2020
Document Transition Report	false
Entity File Number	0-14616
Entity Incorporation, State or Country Code	NJ
Entity Tax Identification Number	22-1935537
Entity Address, Address Line One	6000 Central Highway
Entity Address, City or Town	Pennsauken
Entity Address, State or Province	NJ
Entity Address, Postal Zip Code	08109
City Area Code	856
Local Phone Number	665-9533
Title of 12(b) Security	Common Stock, no par value
Trading Symbol	JJSF
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		18,979,637