A gain controlling apparatus includes a pre-amplifier for roughly adjusting a gain of a generation signal, which is generated on the basis of a reception signal from an optical disc; a variable amplifier for finely adjusting the gain on the basis of the roughly adjusted gain by the pre-amplifier; a memory for storing a plurality of values for adjusting the gain generated during a previous occasion of gain adjustment in time series; and a controlling device for controlling the pre-amplifier at a current occasion of gain adjustment on the basis of the respective stored values for adjusting the gain and controlling the variable amplifier, wherein the controlling device comprises a predicting device for predicting a current adjustment value, namely an adjusted value for the gain roughly adjusted at the current occasion by the pre-amplifier, and the controlling device controls the pre-amplifier on the basis of the predicted current adjustment value.