A method for imaging a welding area, the method comprising: scanning a cross section of a test object in a cross direction orthogonal to a welding direction with an ultrasonic beam, and receiving a reflected signal from the inside of the test object while the cross section is being scanned; and imaging the scanned cross section on the basis of the received reflected signal to inspect a microstructure of the welding area, wherein a reflected wave from the microstructure of the welding area is enhanced by scanning a cross section of the test object orthogonal to the welding direction with a focused ultrasonic beam at a plurality of different positions (P1, P2,...Pn) in the welding direction, and imaging the scanned cross sections on the basis of the resulting ultrasonic received signals, characterised by in the imaging, enhancing the reflected wave from the microstructure of the welding area by subtracting a moving average waveform Ra from a received and digitized signal waveform Rb, extracting the reflected signal from the microstructure of the welding area and amplifying only the extracted reflected signal, and by using the extracted reflected signal, superimposing a plurality of images (B1, B2,...Bn) obtained by scanning at the plurality of positions in the welding direction, and retaining a maximal value of superimposed pixels to generate an output image: B x y = Max Bs x y; s = 1 ∼ n where n is the number of images obtained by scanning at the plurality of positions (P1, P2,...Pn) in the welding direction, and a brightness value at a given position (x,y) in image Bn is expressed as Bn(x,y), where x is a position in the cross direction and y is a position in the depth direction. scanning a cross section of a test object in a cross direction orthogonal to a welding direction with an ultrasonic beam, and receiving a reflected signal from the inside of the test object while the cross section is being scanned; and imaging the scanned cross section on the basis of the received reflected signal to inspect a microstructure of the welding area, wherein a reflected wave from the microstructure of the welding area is enhanced by scanning a cross section of the test object orthogonal to the welding direction with a focused ultrasonic beam at a plurality of different positions (P1, P2,...Pn) in the welding direction, and imaging the scanned cross sections on the basis of the resulting ultrasonic received signals, characterised by in the imaging, enhancing the reflected wave from the microstructure of the welding area by subtracting a moving average waveform Ra from a received and digitized signal waveform Rb, extracting the reflected signal from the microstructure of the welding area and amplifying only the extracted reflected signal, and by using the extracted reflected signal, superimposing a plurality of images (B1, B2,...Bn) obtained by scanning at the plurality of positions in the welding direction, and retaining a maximal value of superimposed pixels to generate an output image: B x y = Max Bs x y; s = 1 ∼ n where n is the number of images obtained by scanning at the plurality of positions (P1, P2,...Pn) in the welding direction, and a brightness value at a given position (x,y) in image Bn is expressed as Bn(x,y), where x is a position in the cross direction and y is a position in the depth direction.