An image encoding/decoding method and apparatus are provided. An image decoding method performed by an image decoding apparatus includes determining whether predetermined splitting is allowed for a current block based on a size of the current block, obtaining information on splitting of the current block based on whether the predetermined splitting is allowed, splitting the current block based on the information on splitting of the current block, and decoding the current block. Whether the predetermined splitting is allowed may be determined based on whether a width or height of the current block is a predetermined sample length.