To regenerate a waste glass wool board to a reclaimed fiber material usable as a raw material for the glass wool board.

A waste material of formed fiber material and an uncured wool are defibrated at the same time and the defibrated waste material and defibrated uncured wool material formed by the simultaneous defibration are supplied to a cyclone of a cyclone dust collector, entangled, mixed and collected to obtain a claimed fiber material containing the defibrated waste material and the defibrated uncured wool in a sufficiently bonded state. The product is free from the trouble of the peeling between the defibrated waste material and the defibrated uncured wool. Accordingly, a fiber board 51 resistant to the peeling between the defibrated waste material and the defibrated uncured wool and having high flexural strength can be produced e.g. by sandwiching the reclaimed fiber material 52 between a pair of uncured wool sheets 53.