Inkjet recording medium and method of manufacturing the same

An inkjet recording medium comprising, on a substrate, an ink-receiving layer comprising inorganic fine particles and an organic nitrogen-containing cationic polyurethane, the organic nitrogen-containing cationic polyurethane being contained in a greater quantity in a half of the ink-receiving layer at a side nearer to the substrate (a near-substrate side) than in a half of the ink-receiving layer at a side further from the substrate (a far-substrate side) when the ink-receiving layer is divided into two equal parts by a plane parallel to the substrate,

• wherein the ink-receiving layer has two or more constituent layers and an uppermost constituent layer lying furthest from the substrate has a thickness of from 0.05 μm to 5 μm and contains colloidal silica,
• wherein the ink-receiving layer further comprises a sulfur compound selected from the group consisting of a thioether compound, a thiourea compound, a disulfide compound, a sulfinic acid compound, a thiocyanic acid compound, a sulfur-containing heterocyclic compound, and a sulfoxide compound,
• the thioether compound being a compound represented by the following formula (1):
• R1—(S—R3)m—S—R2 (1)
• wherein, in formula (1), R1 and R2 each independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, or an alkyl- or aryl-containing group, R1 and R2 may combine with each other to form a ring, provided that at least either R1 or R2 represents an alkyl group substituted with an hydrophilic group or a basic nitrogen-containing group;
• R3 represents an alkylene group which may be substituted and which may have an oxygen atom;
• m represents an integer of 0 to 10, and when m is 1 or more, at least one sulfur atom bound to R3 may be a sulfoxide group or a sulfonyl group;
• the thiourea compound being a compound having at least one structural unit represented by >N—C(═S)—N< per molecule;
• the disulfide compound being a compound represented by the following formula:
• R1—S—S—R2
• wherein, in the formula, R1 and R2 each independently represents an organic group containing a carbon or nitrogen atom bound to the disulfide sulfur;
• the sulfinic acid compound being a compound represented by the following formula:
• R—SO2M
• wherein, in the formula, R represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, or a polymer residue;
• and M represents a hydrogen atom, an alkali metal atom or an ammonium.