Porous silicon/laser dye composite was obtained by efficiently inserting laser dye into porous silicon. The composite shows luminescent property of both the porous silicon and the laser dye when inserting trace dye. Increasing the insert of dye molecules, luminescence of the composite increases, the rise time becomes faster, the pulse width of the luminescence narrows, and the composite shows mainly the luminescent property of laser dye. The luminescence peak position of the composite shifts clearly to the blue compared to that of the same dye in alcohol solution.