This study was conducted to clarify larval movement of the tobacco beetle, Lasioderma serricorne, in whole wheat flour. Thirty adults emerged within 4 days were released in mixed sex on the surface of 3 cm deep whole wheat flour in a PVC case. The case was made of pipe cut into 6 slices to a width of 1 cm in advance and each slice was named R1 to R6 from a bottom side. After adults were allowed to lay eggs for 7 days, they were removed. At the same time, 2 cm more flour was added on the surface of 3 cm flour. Newly hatched larvae could move from oviposition site (R3) to 2 cm upper side or 3 cm down side in the flour. Three weeks later, the number of larvae in each slice was counted. Larvae were observed at all slices and the most larvae were significantly observed in R5 (30.9±2.8%). This result indicates that many larvae move from the oviposition site to upper side, when more flour is deposited on the oviposition site.