In an LED lamp according to one embodiment of the present invention, a PWM control unit 25 performs PWM control of a current i flowing through an LED unit 24 using by driving a pulse at a frequency higher than a predetermined frequency when a frequency of an external alternating current inputted between input terminal parts 20a, 20b is lower than the predetermined frequency, and does not perform PWM control of the current i flowing through the LED unit 24 when a frequency of the external AC inputted between the input terminal parts 20a, 20b is higher than the predetermined frequency. Accordingly, by replacing a previously mounted fluorescent lamp, the LED unit drives pulses at a high frequency and lights up for illumination, regardless of whether a ballast of an illumination device is of a glow starter, rapid starter or inverter lighting type.