Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Jun. 30, 2021	Sep. 10, 2021	Dec. 31, 2020
Cover [Abstract]
SEC Form	10-K
Document Annual Report	true
Document Transition Report	false
Period End date	Jun. 30, 2021
Registrant CIK	0000916907
Entity File Number	0-23406
Registrant Name	SOUTHERN MISSOURI BANCORP, INC.
Entity Incorporation, State or Country Code	MO
Tax Identification Number (TIN)	43-1665523
Entity Address, Address Line One	2991 Oak Grove Road
Entity Address, City or Town	Poplar Bluff
Entity Address, State or Province	MO
Entity Address, Postal Zip Code	63901
City Area Code	573
Local Phone Number	778-1800
Title of 12(b) Security	Common Stock
Trading Symbol	SMBC
Trading Exchange	NASDAQ
Voluntary filer	No
Well-known Seasoned Issuer	No
Current reporting status	Yes
Interactive Data Current	Yes
Filer Category	Accelerated Filer
Small Business	false
Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Shell Company	false
Number of common stock shares outstanding		8,894,568
Fiscal Year End	--06-30
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	FY
Amendment Flag	false
Public Float			$ 242.2