To provide a spotting method which prevents light exudation from occurring at an unit for biochemical analysis.

A plurality of spot regions 14 are made up in the unit for biochemical analysis 10 by pressing a membrane 13 into a plurality of through holes 12 formed in a substrate 11. A thin film 15 made of the membrane 13 being extended by pressure remains on the rear face of the substrate 11. Spotting of a probe solution to the spot region 14 is carried out by a spot head 20. When the spotting is carried out, a pin arrangement plate 21 is pressure welded to the rear face of the substrate 11. Pins 22 are arranged on the pin arrangement plate 21 so that their pitches are identical to arrangement pitches of respective spot regions 14. The pin arrangement plate 21 is positioned so that the pins 22 correspond to spot regions 14, respectively. Respective pins 22 are brought to pierce the thin film 15 by carrying out pressure welding. As a result, pores 23 in the thin film 15 get crushed, thereby preventing the probe solution from osmosing into the spot regions 14 adjacent to each other.