| Document And Entity Information | May 01, 2020 |
| Document Information [Line Items] | |
| Entity, Registrant Name | J&J SNACK FOODS CORP. |
| Document, Type | 8-K |
| Document, Period End Date | May 1, 2020 |
| Entity, Incorporation, State or Country Code | NJ |
| Entity, File Number | 000-14616 |
| 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 |
| Trading Symbol | JJSF |
| Security Exchange Name | NASDAQ |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity, Emerging Growth Company | false |
| Amendment Flag | false |
| Entity, Central Index Key | 0000785956 |
