Entry of water from the terminal portion side to the electronic component side is inhibited. A circuit unit includes: a circuit section including a terminal portion that can be connected to an external terminal, and a body portion to which an electronic component is mounted; a first waterproofing portion that is in intimate contact with a portion to be waterproofed located between the body portion and the terminal portion of the circuit section, and that includes a resin containing an adhesive component; and a second waterproofing portion that is in intimate contact with an outer surface of each of the circuit section and the first waterproofing portion, and that is made of a resin.