A crankshaft flaw detection device for scanning for a flaw detection of a crankshaft including at least two journal sections arranged on the same axial center, a crank pin arranged in an eccentric state between the two journal sections adjacent to each other, and a web in a plate shape for coupling the crank pin and the journal section adjacent to each other, in a state where the journal sections are disposed so as to be approximately horizontal and so as to be capable of turning, comprising: a pair of shaft flaw detection heads (2, 3) capable of sandwiching the crank pin therebetween, and comprising a first probe capable of scanning for a flaw detection in a cylindrical surface of the crank pin and a second probe capable of scanning for a flaw detection in a fillet section which is a coupling section between the crank pin and the web; and a perpendicular surface flaw detection head capable of coming in contact with the crank pin, and comprising a third probe capable of scanning for a flaw detection in a side surface of the web orthogonal to an axial center of the crank pin, characterized in that the crankshaft flaw detection device comprises a base for supporting the perpendicular surface flaw detection head so that the perpendicular surface flaw detection head moves freely on a perpendicular surface orthogonal to the axial center of the journal sections; and the pair of shaft flaw detection heads (2, 3) are coupled to the perpendicular surface flaw detection head, the base includes a slider and a support stand, the slider is configured to be movable in a direction along a rail of the support stand, the crankshaft flaw detection device further comprises a coupling arm, one end of the coupling arm is connected to the perpendicular surface flaw detection head, and the other end of the coupling arm is coupled to the slider for rotation about the slider. a pair of shaft flaw detection heads (2, 3) capable of sandwiching the crank pin therebetween, and comprising a first probe capable of scanning for a flaw detection in a cylindrical surface of the crank pin and a second probe capable of scanning for a flaw detection in a fillet section which is a coupling section between the crank pin and the web; and a perpendicular surface flaw detection head capable of coming in contact with the crank pin, and comprising a third probe capable of scanning for a flaw detection in a side surface of the web orthogonal to an axial center of the crank pin, characterized in that the crankshaft flaw detection device comprises a base for supporting the perpendicular surface flaw detection head so that the perpendicular surface flaw detection head moves freely on a perpendicular surface orthogonal to the axial center of the journal sections; and the pair of shaft flaw detection heads (2, 3) are coupled to the perpendicular surface flaw detection head, the base includes a slider and a support stand, the slider is configured to be movable in a direction along a rail of the support stand, the crankshaft flaw detection device further comprises a coupling arm, one end of the coupling arm is connected to the perpendicular surface flaw detection head, and the other end of the coupling arm is coupled to the slider for rotation about the slider.