A porous cellulose aggregate which has a secondary aggregation structure formed by the aggregation of primary cellulose particles, has a pore volume within a particle of 0.265 cm3/g to 2.625 cm3/g, contains I type crystals, has an average particle diameter of more than 30 μm and 250 μm or less, has a specific surface area of 1.3 to 20 cm2/g, has an angle of repose of 25° or more and less than 44°, and has the property that it collapses in water.
