To provide a method for opening and blending of opened raw cotton capable of affording blended cotton initially having a required blending ratio and extremely readily performable changing its blended ratio even in a midway and an apparatus therefor.

This opening apparatus has carrying belt conveyors 2a and 2b for opened raw cotton and an opening mechanism 3 arranged at a front face in a proceeding direction of the opened raw cotton, and the conveyors 2a and 2b are constituted of plural rows corresponding to kinds to be blended, then the opening mechanism 3 has a raking member 4, thus raked raw cotton is connected to a carrying means with an air stream and required opened raw cotton are laid on respective conveyors 2a and 2b, then the conveyors are run at a prescribed speed ratio corresponding to a blending ratio of the raw cotton laid on the each conveyor 2a and 2b, thus every raw cotton are simultaneously raked by the raking member 4 to perform opening of every raw cotton and blending by a carrying air stream.