Disclosed is an RC oscillator (300) comprising: a bias circuit (310), generating first and second bias currents (Ia, Ib), and outputting a charging current (IL) proportional to a total bias current that is the sum of the first and second bias currents, wherein the ratio (Ia/Ib) of the first bias current to the second bias current has a positive temperature coefficient; and an oscillation circuit (320), for periodically charging a capacitor (C0, C1) using the charging current output by the bias circuit, and using a voltage across a resistor (R2) through which the second bias current or a current proportional thereto flows as a reference voltage to compare with a charging voltage (Vcap) on the capacitor, so as to obtain a periodically oscillating clock signal (CLK, CLKB). Thus, the present disclosure can compensate the positive temperature coefficient of the subsequent delay and realize the RC oscillator with low temperature drift by making the charging time of the capacitor have a negative temperature coefficient.