A cutting tool replacement member comprising: a lower surface which serves as a seating surface; an upper surface which is opposed to the lower surface; and a side surface which is connected to the upper surface and the lower surface, wherein: when seen from a top view, the upper surface comprises, in an intersection between the upper surface and the side surface, a reference side edge and an inclined side edge which is inclined relative to the reference side edge; the side surface includes a first side surface part which is connected to the reference side edge of the upper surface, and a second side surface part which is connected to the inclined side edge of the upper surface; and at least one of the first side surface part and the second side surface part is provided with an overhanging part which is, when seen from a top view, protruding outward with respect to the reference side edge or the inclined side edge, characterised in that the second side surface part or a side surface part which leads thereto comprises a tool engagement part which is further protruding than its adjacent portion in a direction intersecting with the first side surface part or an extension plane thereof. a lower surface which serves as a seating surface; an upper surface which is opposed to the lower surface; and a side surface which is connected to the upper surface and the lower surface, wherein: when seen from a top view, the upper surface comprises, in an intersection between the upper surface and the side surface, a reference side edge and an inclined side edge which is inclined relative to the reference side edge; the side surface includes a first side surface part which is connected to the reference side edge of the upper surface, and a second side surface part which is connected to the inclined side edge of the upper surface; and at least one of the first side surface part and the second side surface part is provided with an overhanging part which is, when seen from a top view, protruding outward with respect to the reference side edge or the inclined side edge, characterised in that the second side surface part or a side surface part which leads thereto comprises a tool engagement part which is further protruding than its adjacent portion in a direction intersecting with the first side surface part or an extension plane thereof. when seen from a top view, the upper surface comprises, in an intersection between the upper surface and the side surface, a reference side edge and an inclined side edge which is inclined relative to the reference side edge; the side surface includes a first side surface part which is connected to the reference side edge of the upper surface, and a second side surface part which is connected to the inclined side edge of the upper surface; and at least one of the first side surface part and the second side surface part is provided with an overhanging part which is, when seen from a top view, protruding outward with respect to the reference side edge or the inclined side edge, characterised in that the second side surface part or a side surface part which leads thereto comprises a tool engagement part which is further protruding than its adjacent portion in a direction intersecting with the first side surface part or an extension plane thereof.