A porous cellulose aggregate having a secondary aggregate structure formed by aggregation of primary cellulose particles, a pore volume within a particle of 0.265 cm 3 /g-2.625 cm 3 /g the pore volume being calculated as the clear peak area in the range of pore diameter of 0.1-1.5 μm in the pore size distribution obtained by measurement using a autopore type 9520 (Commercial Name, made by Shimadzu Corporation) at the initial pressure of 20 KPa of a sample dried at room temperature for 15 hours under reduced pressure, containing type I crystals, and having an average particle size measured using a Ro-tap sieve shake and expressed as the accumulated weight 50% particle size of more than 30 μm and 250 μm or less, a specific surface area measured using the BET method of 0.1 m 2 /g or more and less than 20 m 2 /g, a repose angle of 25° or more and less than 44° the repose angle being measured as an angle between the bottom of the device and the top layer of the cellulose powder when cellulose powder is dropped to the slit at 3 g/minute using a Sugihara type repose angle measuring device (slit size: depth 10 mm x width 50 mm x height 140 mm, a protractor placed at the position of 50 mm width) and a quantitative feeder, a swelling degree of 5% or more wherein the swelling degree is defined as (V 2 -V 1)/V 1 x 100 obtained from the volume (V 1) of about 10 g of powder which is slowly poured into a cylindrical container having 100 cm 3 capacity and the volume (V 2) of the same powder when about 50 cm 3 of pure water is added to the powder and the result is mixed so that the powder is thoroughly wetted and then left standing for 8 hours, and properties to disintegrate in water, wherein the porous cellulose aggregate is obtained by a production method comprising: a step of obtaining a dispersion (hereinafter may also be designated as a cellulose dispersion) comprising a natural cellulose material in which primary cellulose particles have an average particle size of 10 μm or larger and less than 50 μm the average particle size being a cumulative volume 50% particle obtained by measuring the cellulose dispersed in water using a laser diffraction particle size distribution analyzer (HORIBA, LA-910 (Commercial Name)) after ultrasonic treatment of one minute, at refractive index of 1.20, average width of 2-30 μm the average width being obtained as the average of three representative primary cellulose particles by optionally drying primary cellulose particles consisting of a natural cellulose substance, placing them on a sample platform covered with a carbon tape, vacuum coating them with platinum/palladium (thickness of vapor deposited film is 20 nm or less), and observing them using JSM-5510V (Commercial Name) made by JASCO Corporation, at an acceleration voltage of 6 kV at a magnification of x250 and average thickness of 0.5-5 μm the average thickness being obtained as the average of three representative primary cellulose particles by optionally drying primary cellulose particles consisting of a natural cellulose substance, placing them on a sample platform covered with a carbon tape, vacuum coating with gold, and then excising a cross section of a primary cellulose particle by Ga ion beam using a converging ion beam manufacturing apparatus (Hitachi, Ltd. FB-2100 (Commercial Name)) and observing it at an acceleration voltage of 6 kV at a magnification of x1500, and a step of drying thus obtained cellulose dispersion. a step of obtaining a dispersion (hereinafter may also be designated as a cellulose dispersion) comprising a natural cellulose material in which primary cellulose particles have