To provide a biological liquid waste treatment apparatus and a biological liquid waste treatment method, capable of sufficiently decomposing oil or fat separated from oil-containing liquid waste.

The oil-containing liquid waste is separated into liquid waste containing the oil or fat at a lower concentration and liquid waste containing the oil or fat at a higher concentration by means of an oil concentration/separation apparatus 1; the liquid waste containing the oil or fat at a lower concentration is introduced into a methane fermentation apparatus 2, and subjected to a methane fermentation treatment using microbial sludge, while the liquid waste containing the oil or fat at a higher concentration is introduced into an oil decomposition apparatus 3 and stirred by means of a stirring apparatus 11. The state of the oil in the liquid waste containing the oil or fat at a higher concentration is acquired by means of an oil state acquisition means 10, and the stirring condition of the stirring apparatus 11 is changed in accordance with the state of the oil. According to this, the oil contained in the high-concentration oil liquid waste is surely decomposed using the microbial sludge while suppressing the formation of masses of the oil.