Document and Entity Information - USD ($)	12 Months Ended
	Apr. 30, 2015	Aug. 12, 2015	Oct. 31, 2014
Document Type	10-K
Amendment Flag	false
Document Period End Date	Apr. 30, 2015
Trading Symbol	jigd
Entity Registrant Name	JOYMAIN INTERNATIONAL DEVELOPMENT GROUP INC.
Entity Central Index Key	0001520007
Current Fiscal Year End Date	--04-30
Entity Filer Category	Smaller Reporting Company
Entity Common Stock, Shares Outstanding		1,120,343,373
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Well Known Seasoned Issuer	No
Entity Public Float			$ 0
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	FY