A waterproof electronic component, comprising: an electronic substrate including a contact point (S, T) for electric connection; a housing including a first housing wall along the electronic substrate and containing the electronic substrate; a light-emitting diode present between the electronic substrate and the housing and including (i) a light-emitting section including a light-emitting element and (ii) a terminal pin protruding from the light-emitting section; a light-guiding seat section configured to guide light of the light-emitting section to outside of the housing; and a sealing section including a resin with which an area surrounded by the electronic substrate and the housing is filled, wherein the first housing wall includes: a seat section having a seating surface (b) on which the electronic substrate is placed; and a window section in which the light-guiding seat section is fitted and which has an open hole, the light-emitting diode is oriented such that the light-emitting section is supported by the light-guiding seat section in a state where a first end of the terminal pin protrudes in a direction crossing the seating surface (b), the electronic substrate is present on the seat section in a state where the first end of the terminal pin is connected to the contact point, the light-guiding seat section includes: a light-guiding seat section main body having a depression in which the light-emitting section is fitted and which supports the light-emitting section; a plate surface section present around the light-guiding seat section main body and in surface contact with an area around the open hole; and a contact section protruding from the light-guiding seat section main body in a direction crossing the seating surface (b) and present in contact with the electronic substrate, and the light-guiding seat section is sandwiched between and held by the first housing wall and the electronic substrate by means of the plate surface section and the contact section, characterized in that the light-guiding seat section further includes an exposure portion fitted in the open hole and exposed to the outside of the housing, and the plate surface section is in a form of a step section extending outwardly radially from a periphery of the exposure portion. an electronic substrate including a contact point (S, T) for electric connection; a housing including a first housing wall along the electronic substrate and containing the electronic substrate; a light-emitting diode present between the electronic substrate and the housing and including (i) a light-emitting section including a light-emitting element and (ii) a terminal pin protruding from the light-emitting section; a light-guiding seat section configured to guide light of the light-emitting section to outside of the housing; and a sealing section including a resin with which an area surrounded by the electronic substrate and the housing is filled, wherein the first housing wall includes: a seat section having a seating surface (b) on which the electronic substrate is placed; and a window section in which the light-guiding seat section is fitted and which has an open hole, a seat section having a seating surface (b) on which the electronic substrate is placed; and a window section in which the light-guiding seat section is fitted and which has an open hole, the light-emitting diode is oriented such that the light-emitting section is supported by the light-guiding seat section in a state where a first end of the terminal pin protrudes in a direction crossing the seating surface (b), the electronic substrate is present on the seat section in a state where the first end of the terminal pin is connected to the contact point, the light-guiding seat section includes: a light-guiding seat section main body having a depression in which the light-emitting section is fitted and which supports the light-emitting section; a plate surface section present around the light-guiding seat section main body and in surface contact with an area around the open hole; and a contact section protruding from the light-guiding seat section main body in a direction crossing the seating surface (b) and present in contact with the electronic substrate, and a light-guiding seat section main body having a depression in which the light-emitting section is fitted and which supports the light-emitting section; a plate surface section present around the light-guiding seat section main body and in surface contact with an area around the open hole; and a contact section protruding from the light-guiding seat section main body in a direction crossing the seating surface (b) and present in contact with the electronic substrate, and the light-guiding seat section is sandwiched between and held by the first housing wall and the electronic substrate by means of the plate surface section and the contact section, the light-guiding seat section further includes an exposure portion fitted in the open hole and exposed to the outside of the housing, and the plate surface section is in a form of a step section extending outwardly radially from a periphery of the exposure portion.