Document and Entity Information - shares	6 Months Ended
	Jul. 31, 2019	Sep. 05, 2019
Document and Entity Information
Document Type	10-Q
Document Period End Date	Jul. 31, 2019
Entity Registrant Name	MESABI TRUST
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		13,120,010
Current Fiscal Year End Date	--01-31
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q2
Entity Central Index Key	0000065172
Amendment Flag	false