To maintain and to improve the forest ecosystem, it is necessary to reveal the threshold of lethal drought stress in the forest plantation species. We used two widely planted Japanese conifers (Japanese cedar and Japanese black pine) to derive the vulnerability curves (VCs) and to visualize the spatial distributions of water loss using compact magnetic resonance imaging. Although values of 50 % loss of hydraulic conductivity (P₅₀), which mean the threshold of lethal drought stress in the stems of conifers, were similar, trends in the VCs differed between species. In Japanese cedar, large embolized areas in xylem developed under mild drought stress, and the VC showed a gradually increasing trend. On the other hand, in Japanese black pine, embolisms were hardly detected down to a pressure of –4 MPa, and the VC showed a steeply increasing trend at –5 MPa or lower. Data on both P₅₀ and the VC slopes may be required for improved understanding of interspecific differences in drought tolerance.