To provide a method and an apparatus for cutting a light-weight cellular concrete plate, capable of increasing a cutting speed so as to obtain an increased productivity.

At first, a rotary cutting blade 11 on the upstream side of a cutting apparatus is used to cut into a light-weight cellular concrete plate from one side thereof till its middle position including one reinforcing mat. Then, a rotary cutting blade 12 on the downstream side of the cutting apparatus is caused to enter a first groove formed by the above cutting operation, to cut into the remaining portion of the concreted plate including the other, reinforcing mat. Afterwards, a third rotary cutting blade 13 is used to cut into the concrete plate from the opposite side thereof, forming a second cutting groove lined up with the above first groove. Finally, the rotary cutting blade 12 on the downstream side is used to completely cut through the concrete plate.