The present invention provides a lithographic printing plate material for silver complex diffusion transfer process by scanning type exposure which comprises a film support and, provided thereon, at least a silver halide emulsion layer and a surface physical development nuclei layer, wherein water content in the whole lithographic printing plate material including the support is 1.5% or less. Preferably, the silver halide emulsion comprises about 95 mol % or more of silver chloride, 90% by weight or more of the silver halide grains have a size within .+-.40% of average grain size, the silver halide grains have an average grain size of about 0.3.mu.-about 1.0.mu., and the surface of the grains is replaced with about 0.1 mol %-about 3.0 mol % of an iodide per 1 mol of the silver halide.