Cover - USD ($) $ in Billions	12 Months Ended
	Sep. 30, 2021	Nov. 01, 2021	Mar. 31, 2021
Document Type	10-K
Amendment Flag	false
Document Annual Report	true
Document Transition Report	false
Document Period End Date	Sep. 30, 2021
Document Fiscal Period Focus	FY
Document Fiscal Year Focus	2021
Current Fiscal Year End Date	--09-30
Entity File Number	001-33177
Entity Registrant Name	MONMOUTH REAL ESTATE INVESTMENT CORPORATION
Entity Central Index Key	0000067625
Entity Tax Identification Number	22-1897375
Entity Incorporation, State or Country Code	MD
Entity Address, Address Line One	101 Crawfords Corner Road
Entity Address, Address Line Two	Suite 1405
Entity Address, City or Town	Holmdel
Entity Address, State or Province	NJ
Entity Address, Postal Zip Code	07733
City Area Code	732
Local Phone Number	577-9996
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
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 Public Float			$ 1.7
Entity Common Stock, Shares Outstanding		98,339,416
ICFR Auditor Attestation Flag	true
Common Stock [Member]
Title of 12(b) Security	Common Stock
Trading Symbol	MNR
Security Exchange Name	NYSE
6.125% Series C Cumulative Redeemable Preferred Stock [Member]
Title of 12(b) Security	6.125% Series C Cumulative Redeemable Preferred Stock
Trading Symbol	MNR-PC
Security Exchange Name	NYSE