A keyboard comprising: a housing which supports a keybutton to be capable of reciprocating in an operating direction of the keybutton; and a substrate on which an operation detection portion of the keybutton is provided, wherein the keybutton supported by the housing is disposed to oppose the operation detection portion on an axial line along the operating direction of the keybutton, wherein a light source is provided further on an outer side than the operation detection portion on the substrate when the light source is viewed from the axial direction of the axial line, wherein a light guide member which guides light from the light source to a keytop of the keybutton is formed of a material having a refractive index which is higher than a refractive index of the air, and the light guide member is provided in the housing, wherein the light guide member includes an incident portion disposed to oppose the light source in the axial direction of the axial line, an emitting portion disposed to oppose the keytop at a position hidden by the keybutton when the emitting portion is viewed from the axial direction of the axial line, and a guide portion which guides the light, from the light source, incident from the incident portion to the emitting portion, characterized in that an incident surface of the incident portion which opposes the light source is formed in a shape of a curved surface that protrudes to the light source side, the guide portion has a first boundary surface to which the light that is refracted at the incident surface and is incident in the incident portion reaches, the incident surface is formed to have a radius of curvature by which the light refracted at the incident surface enters the first boundary surface at an incident angle which is greater than a critical angle of the light on the first boundary surface defined by the refractive index of the light guide member and the refractive index of the air, an emitting surface of the emitting portion which opposes the keytop is formed in a shape of a curved surface that is concaved in a recessed shape in a direction of being away from the keytop, and the emitting surface is formed to have a radius of curvature by which the light that has reached the emitting surface through an inside of the emitting portion is refracted at the emitting surface and an advancing direction of the refracted light is a direction toward the keytop. a housing which supports a keybutton to be capable of reciprocating in an operating direction of the keybutton; and a substrate on which an operation detection portion of the keybutton is provided, wherein the keybutton supported by the housing is disposed to oppose the operation detection portion on an axial line along the operating direction of the keybutton, wherein a light source is provided further on an outer side than the operation detection portion on the substrate when the light source is viewed from the axial direction of the axial line, wherein a light guide member which guides light from the light source to a keytop of the keybutton is formed of a material having a refractive index which is higher than a refractive index of the air, and the light guide member is provided in the housing, wherein the light guide member includes an incident portion disposed to oppose the light source in the axial direction of the axial line, an emitting portion disposed to oppose the keytop at a position hidden by the keybutton when the emitting portion is viewed from the axial direction of the axial line, and a guide portion which guides the light, from the light source, incident from the incident portion to the emitting portion, characterized in that an incident surface of the incident portion which opposes the light source is formed in a shape of a curved surface that protrudes to the light source side, the guide portion has a first boundary surface to which the light that is refracted at the incident surface and is incident in the incident portion reaches, the incident surface is formed to have a radius of curvature by which the light refracted at the incident surface enters the first boundary surface at an incident angle which is greater than a critical angle of the light on the first boundary surface defined by the refractive index of the light guide member and the refractive index of the air, an emitting surface of the emitting portion which opposes the keytop is formed in a shape of a curved surface that is concaved in a recessed shape in a direction of being away from the keytop, and the emitting surface is formed to have a radius of curvature by which the light that has reached the emitting surface through an inside of the emitting portion is refracted at the emitting surface and an advancing direction of the refracted light is a direction toward the keytop.