A cutting tool comprising a cutting edge member , wherein the cutting edge member includes: a cutting edge which is formed in a corner portion (20C1) of a connection portion which connects an end surface and a side surface ; a first wall surface (20B1) which includes a concave surface which is provided at a position through which an imaginary plane (IP) determined so as to halve the corner portion passes, and is formed to be depressed in a direction away from an intersection point (P) of the imaginary plane (IP) and the corner portion (20C1) in an end view when viewed from a direction facing the end surface ; a second wall surface (20B2) which includes a convex surface which is provided to be connected to the first wall surface (20B1) at a position spaced apart from the imaginary plane (IP), and is protruded in a direction opposite to the direction in which the concave surface (20B1) is depressed in the end view; and a third wall surface (20B3) which includes a convex surface which is provided to be connected to the first wall surface (20B1) at a position spaced apart from the imaginary plane (IP) on an opposite side to the second wall surface (20B2) across to the imaginary plane (IP), and is protruded in a direction opposite to the direction in which the concave surface (20B1) is depressed in the end view; characterised in that the cutting edge member further includes a fourth wall surface (20B4) which is provided in an area which is between the first wall surface (20B1) and the intersection point (IP) in the end view and through which the imaginary plane (IP) passes, includes a convex surface which is protruded in a direction opposite to the direction in which the concave surface (20B1) is depressed in the end view, and has a height smaller than heights of the second wall surface (20B2) and the third wall surface (20B3) in a side view when viewed from a direction facing the side surface . a cutting edge which is formed in a corner portion (20C1) of a connection portion which connects an end surface and a side surface ; a first wall surface (20B1) which includes a concave surface which is provided at a position through which an imaginary plane (IP) determined so as to halve the corner portion passes, and is formed to be depressed in a direction away from an intersection point (P) of the imaginary plane (IP) and the corner portion (20C1) in an end view when viewed from a direction facing the end surface ; a second wall surface (20B2) which includes a convex surface which is provided to be connected to the first wall surface (20B1) at a position spaced apart from the imaginary plane (IP), and is protruded in a direction opposite to the direction in which the concave surface (20B1) is depressed in the end view; and a third wall surface (20B3) which includes a convex surface which is provided to be connected to the first wall surface (20B1) at a position spaced apart from the imaginary plane (IP) on an opposite side to the second wall surface (20B2) across to the imaginary plane (IP), and is protruded in a direction opposite to the direction in which the concave surface (20B1) is depressed in the end view; characterised in that the cutting edge member further includes a fourth wall surface (20B4) which is provided in an area which is between the first wall surface (20B1) and the intersection point (IP) in the end view and through which the imaginary plane (IP) passes, includes a convex surface which is protruded in a direction opposite to the direction in which the concave surface (20B1) is depressed in the end view, and has a height smaller than heights of the second wall surface (20B2) and the third wall surface (20B3) in a side view when viewed from a direction facing the side surface . <EOS>