An accessory removably attachable to a camera body and including a plurality of terminals, the accessory comprising: a detection terminal (LDET for causing the camera body to detect that the accessory is attached thereto; a first power supply terminal (VBAT) through which a first power supply voltage is supplied from the camera body; a second power supply terminal (V33) through which a second power supply voltage is supplied from the camera body; a ground terminal (PGND) used as a ground potential; a ready terminal (RDY) used to indicate whether or not communication with the camera body is allowed; a first clock terminal (CLK) that receives a first clock signal having a first cycle from the camera body; a first data terminal (DATAB) that receives a first data signal from the camera body in synchronization with the first clock signal; a second data terminal (DATAL) that outputs a second data signal to the camera body in synchronization with the first clock signal; a second clock terminal (HCLK) that outputs a second clock signal having a second cycle to the camera body; a third data terminal (HDATA) that outputs a third data signal to the camera body in synchronization with the second clock signal; a first circuit to which the first power supply voltage is supplied through the first power supply terminal; and a second circuit to which the second power supply voltage is supplied through the second power supply terminal, wherein: the ground terminal is used as a ground potential for the first circuit and the second circuit; and a distance between the second clock terminal and the first power supply terminal is longer than a distance between the first clock terminal and the first power supply terminal. a detection terminal (LDET for causing the camera body to detect that the accessory is attached thereto; a first power supply terminal (VBAT) through which a first power supply voltage is supplied from the camera body; a second power supply terminal (V33) through which a second power supply voltage is supplied from the camera body; a ground terminal (PGND) used as a ground potential; a ready terminal (RDY) used to indicate whether or not communication with the camera body is allowed; a first clock terminal (CLK) that receives a first clock signal having a first cycle from the camera body; a first data terminal (DATAB) that receives a first data signal from the camera body in synchronization with the first clock signal; a second data terminal (DATAL) that outputs a second data signal to the camera body in synchronization with the first clock signal; a second clock terminal (HCLK) that outputs a second clock signal having a second cycle to the camera body; a third data terminal (HDATA) that outputs a third data signal to the camera body in synchronization with the second clock signal; a first circuit to which the first power supply voltage is supplied through the first power supply terminal; and a second circuit to which the second power supply voltage is supplied through the second power supply terminal, wherein: the ground terminal is used as a ground potential for the first circuit and the second circuit; and a distance between the second clock terminal and the first power supply terminal is longer than a distance between the first clock terminal and the first power supply terminal. the ground terminal is used as a ground potential for the first circuit and the second circuit; and a distance between the second clock terminal and the first power supply terminal is longer than a distance between the first clock terminal and the first power supply terminal.