Abstract: [Problem] Provided is a method for producing an opened fibre bundle which has a good opened state, excellent resin impregnation properties, and excellent compatibility with a matrix resin, with high productivity. [Problem to be Solved] Disclosed is an opened carbon fibre bundle, wherein particles having a volume average particle size D50 of 1 ?m to 13 ?m and a volume average particle size D90 of 13 ?m or less are comprised in a carbon fibre bundle and a method for producing an opened carbon fibre bundle, comprising the step of bringing a carbon fibre bundle into contact with a fibre opening solution comprising the particles and an organic solvent.

Abstract: [Problem] Provided is a method for producing an opened fibre bundle which enables the production of an opened fibre bundle having a good opened state, excellent resin impregnation properties, and excellent compatibility with a matrix resin. [Problem to be Solved] Disclosed is a method for producing an opened carbon fibre bundle, comprising the step of bringing a carbon fibre bundle comprising a plurality of carbon fibres to which a sizing agent is attached into contact with a fibre opening solution comprising particles having an average particle size (d50) of 1 ?m to 30 ?m and an organic solvent.