There are provided a brake pedal sensor and a stop lamp lighting device in a vehicle, which are capable of controlling blinking of a stop lamp in a simple configuration. The brake pedal sensor includes: a stop lamp switching section which outputs a switch signal; a brake position sensor section which outputs a brake position signal; and a logic circuit section for receiving the switch signal and a blinking signal generated by the brake position signal are inputted, and which outputs a control signal for controlling lighting and blinking of the stop lamp. Using this brake pedal sensor allows configuration of the stop lamp lighting device in a simpler manner.