An antibacterial layer-attached base material comprising: a base material; and an antibacterial layer which is disposed on at least a part of the surface of the base material, wherein the antibacterial layer contains at least one antibacterial agent containing silver, wherein the amount of silver ions per a unit area measured in the following extraction test is 15 to 50 ng/cm 2, wherein, in the extraction test, the amount of silver ions per a unit area is obtained by using a 1/500 common broth medium defined in JIS Z 2801:2010 as an extraction liquid, controlling the temperature of the extraction liquid so as to be at 35 ± 1°C, bringing the extraction liquid into contact with the antibacterial layer in the antibacterial layer-attached base material for an hour, measuring the amount of silver ions extracted in the extraction liquid, and dividing the obtained value by the contact area of the antibacterial layer with respect to the extraction liquid; the unit of the amount of silver ions is ng; the unit of the contact area is cm 2; and the unit of the amount of silver ions per a unit area is ng/cm 2, wherein the antibacterial layer is formed by subjecting a curable composition having at least a monomer having a hydrophilic group and an antibacterial agent containing silver to a curing treatment, wherein the hydrophilic group in the monomer which has a hydrophilic group contains a polyoxyalkylene group, wherein the antibacterial agent is a silver-supporting carrier containing a carrier and silver which is supported on the carrier, wherein the carrier is a ceramic carrier, and wherein the hydrophilic monomer is a compound represented by the following Formula: wherein in Formula R 1 represents a substituent selected from a hydrocarbon group which may have a hetero atom or a hydrophilic group; R 2 represents a polymerizable group; L 1 represents a single bond or a divalent linking group selected from the group consisting of: -O-, -CO-, - NH-, -CO-NH-, -COO-, -O-COO-, an alkylene group, an arylene group, a heteroaryl group, and a combination thereof; L 2 represents the polyoxyalkylene group, wherein the polyoxyalkylene group means a group represented by the following Formula: Formula *-(OR 3) m -* wherein in Formula, R 3 represents an alkylene group; m represents an integer of 2 or more; * represents a bonding position; and n represents an integer of 1 to 4, and wherein the water contact angle of the surface of the antibacterial layer is less than or equal to 40°. a base material; and an antibacterial layer which is disposed on at least a part of the surface of the base material, wherein the antibacterial layer contains at least one antibacterial agent containing silver, wherein the amount of silver ions per a unit area measured in the following extraction test is 15 to 50 ng/cm 2, wherein, in the extraction test, the amount of silver ions per a unit area is obtained by using a 1/500 common broth medium defined in JIS Z 2801:2010 as an extraction liquid, controlling the temperature of the extraction liquid so as to be at 35 ± 1°C, bringing the extraction liquid into contact with the antibacterial layer in the antibacterial layer-attached base material for an hour, measuring the amount of silver ions extracted in the extraction liquid, and dividing the obtained value by the contact area of the antibacterial layer with respect to the extraction liquid; the unit of the amount of silver ions is ng; the unit of the contact area is cm 2; and the unit of the amount of silver ions per a unit area is ng/cm 2, wherein the antibacterial layer is formed by subjecting a curable composition having at least a monomer having a hydrophilic group and an antibacterial agent containing silver to a curing treatment, wherein the hydrophilic group in the monomer which has a hydrophilic group contains a polyoxyalkylene group, wherein the antibacterial agent is a silver-supporting carrier containing a carrier and silver which is supported on the carrier, wherein the carrier is a ceramic carrier, and wherein the hydrophilic monomer is a compound represented by the following Formula: wherein in Formula R 1 represents a substituent selected from a hydrocarbon group which may have a hetero atom or a hydrophilic group; R 2 represents a polymerizable group; L 1 represents a single bond or a divalent linking group selected from the group consisting of: -O-, -CO-, - NH-, -CO-NH-, -COO-, -O-COO-, an alkylene group, an arylene group, a heteroaryl group, and a combination thereof; L 2 represents the polyoxyalkylene group, wherein the polyoxyalkylene group means a group represented by the following Formula: Formula *-(OR 3) m -* wherein in Formula, R 3 represents an alkylene group; m represents an integer of 2 or more; * represents a bonding position; and n represents an integer of 1 to 4, and wherein the water contact angle of the surface of the antibacterial layer is less than or equal to 40°. wherein in Formula, R 3 represents an alkylene group; m represents an integer of 2 or more; * represents a bonding position; and n represents an integer of 1 to 4, and wherein the water contact angle of the surface of the antibacterial layer is less than or equal to 40°.