Document and Entity Information - USD ($)	12 Months Ended
	Jan. 31, 2020	Apr. 27, 2020	Jul. 31, 2019
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Jan. 31, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Entity Registrant Name	MITCHAM INDUSTRIES INC
Entity Central Index Key	0000926423
Current Fiscal Year End Date	--01-31
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Emerging Growth Company	false
Entity Small Business	true
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		12,182,233
Entity Public Float			$ 49,096,243