A disposable undergarment having a liquid-absorbent panel that includes a body fluid absorbing/holding layer formed with a plurality of depressions each extending in the thickness direction thereof and a nonwoven fabric layer placed upon upper surface of the absorbing/holding layer. Heat-sealable fibers contained in the absorbing/holding layer are heat-sealed with the nonwoven fabric layer over contacting surfaces of these absorbing/holding layer and the nonwoven fabric layer. Furthermore, the nonwoven fabric layer is partially engaged in the depressions of the absorbing/holding layer so that the heat-sealable synthetic fibers contained in the absorbing/holding layer are heat-sealed with the nonwoven fabric layer also over contacting surfaces of these two layers in the respective depressions.