Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Jun. 30, 2020	Sep. 11, 2020	Dec. 31, 2019
Cover [Abstract]
Registrant CIK	0000916907
Fiscal Year End	--06-30
Registrant Name	SOUTHERN MISSOURI BANCORP, INC.
SEC Form	10-K
Document Annual Report	true
Document Transition Report	false
Period End date	Jun. 30, 2020
Entity File Number	0-23406
Trading Symbol	SMBC
Trading Exchange	NASDAQ
Tax Identification Number (TIN)	43-1665523
Number of common stock shares outstanding		9,126,625
Public Float			$ 298.2
Filer Category	Accelerated Filer
Current reporting status	Yes
Interactive Data Current	Yes
Voluntary filer	No
Well-known Seasoned Issuer	No
Shell Company	false
Small Business	false
Emerging Growth Company	false
Entity Incorporation, State or Country Code	MO
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
Amendment Flag	false
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY