Note 4 - Mineral Properties - Costs Incurred for Exploration and Evaluation Activities (Details) - CAD ($)		3 Months Ended		9 Months Ended
		Feb. 28, 2019	Feb. 28, 2018	Feb. 28, 2019	Feb. 28, 2018
Exploration expenditures (notes 4 and 5)		$ 1,071,392	$ 1,623,436	$ 4,218,191	$ 4,075,384
North Bullfrog [Member]
Exploration expenditures (notes 4 and 5)	[1]			466,980	913,003
Mother Lode Property [Member]
Exploration expenditures (notes 4 and 5)	[2]			3,751,211	3,162,381
Assay [Member]
Exploration expenditures (notes 4 and 5)				442,879	620,954
Assay [Member] | North Bullfrog [Member]
Exploration expenditures (notes 4 and 5)				2,990	44,148	[1]
Assay [Member] | Mother Lode Property [Member]
Exploration expenditures (notes 4 and 5)	[2]			439,889	576,806
Drilling [Member]
Exploration expenditures (notes 4 and 5)				1,439,593	1,420,406
Drilling [Member] | North Bullfrog [Member]
Exploration expenditures (notes 4 and 5)	[1]			1,239
Costs Recovered for Exploration and Evaluation Activities, Gross	[1]				(3,265)
Drilling [Member] | Mother Lode Property [Member]
Exploration expenditures (notes 4 and 5)	[2]			1,438,354	1,423,671
Equipment rental [Member]
Exploration expenditures (notes 4 and 5)				49,655	81,376
Equipment rental [Member] | North Bullfrog [Member]
Exploration expenditures (notes 4 and 5)					15,698	[1]
Equipment rental [Member] | Mother Lode Property [Member]
Exploration expenditures (notes 4 and 5)	[2]			49,655	65,678
Field Costs [Member]
Exploration expenditures (notes 4 and 5)				188,113	268,494
Field Costs [Member] | North Bullfrog [Member]
Exploration expenditures (notes 4 and 5)	[1]			356	32,121
Field Costs [Member] | Mother Lode Property [Member]
Exploration expenditures (notes 4 and 5)	[2]			187,757	236,373
Geological Geophysical [Member]
Exploration expenditures (notes 4 and 5)				511,681	523,421
Geological Geophysical [Member] | North Bullfrog [Member]
Exploration expenditures (notes 4 and 5)	[1]			28,362	66,473
Geological Geophysical [Member] | Mother Lode Property [Member]
Exploration expenditures (notes 4 and 5)	[2]			483,319	456,948
Land Maintenance and Tenure [Member]
Exploration expenditures (notes 4 and 5)				595,452	393,676
Land Maintenance and Tenure [Member] | North Bullfrog [Member]
Exploration expenditures (notes 4 and 5)	[1]			337,178	267,977
Land Maintenance and Tenure [Member] | Mother Lode Property [Member]
Exploration expenditures (notes 4 and 5)	[2]			258,274	125,699
Permits [Member]
Exploration expenditures (notes 4 and 5)				98,453	98,649
Permits [Member] | North Bullfrog [Member]
Exploration expenditures (notes 4 and 5)	[1]			7,546	6,395
Permits [Member] | Mother Lode Property [Member]
Exploration expenditures (notes 4 and 5)	[2]			90,907	92,254
Studies [Member]
Exploration expenditures (notes 4 and 5)				804,673	588,628
Studies [Member] | North Bullfrog [Member]
Exploration expenditures (notes 4 and 5)	[1]			85,578	473,213
Studies [Member] | Mother Lode Property [Member]
Exploration expenditures (notes 4 and 5)	[2]			719,095	115,415
Travel [Member]
Exploration expenditures (notes 4 and 5)				87,692	79,780
Travel [Member] | North Bullfrog [Member]
Exploration expenditures (notes 4 and 5)				3,731	10,243	[1]
Travel [Member] | Mother Lode Property [Member]
Exploration expenditures (notes 4 and 5)	[2]			$ 83,961	$ 69,537

[1] North Bullfrog Project, Nevada The Company's North Bullfrog project consists of certain leased patented lode mining claims and federal unpatented mining claims owned 100% by the Company.

[2] Mother Lode Property, Nevada Pursuant to a purchase agreement made effective June 9, 2017 between Corvus Nevada and Goldcorp USA, Inc. ("Goldcorp USA"), Corvus Nevada has acquired 100% of the Mother Lode property (the "Mother Lode Property"). In addition, Corvus Nevada staked two additional adjacent claim blocks to the Mother Lode Property. In connection with the acquisition, the Company issued 1,000,000 common shares at a price of $0.81 per common share to Goldcorp USA. The Mother Lode Property is subject to an NSR in favour of Goldcorp USA. The NSR pays 1% from production at the Mother Lode Property when the price of gold is less than USD 1,400 per ounce and an additional 1% NSR for a total of 2% NSR when gold price is greater than or equal to USD 1,400 per ounce.