PURPOSE: To provide the subject elastic composite material suitable for the waist part or the crotch part of a disposable diaper, etc.

CONSTITUTION: This invention is an elastic composite material composed of a non-expanded and non-crimped sheet-shaped base material unrecoverably expandable in the cross direction (CD) of the sheet and a relaxed sheet-shaped elastomer bonded to the above-mentioned base material continuously in the longitudinal direction (MD) of the sheet and discontinuously in the (CD) direction and its production method. The above-mentioned elastic composite material is suitable especially for the waist part and the crotch part of a disposable diaper, etc., stable, highly expandable, soft to the skin and readily producible.