To provide an LED illumination lamp capable of carrying out adjustment of beam angles, and with a stable light distribution.

A straight-tube LED illumination lamp 10 includes an LED substrate 11 arranged with a plurality of LEDs 12 and a cylindrical cover 20 covering the LED substrate 11, and the cover 20 includes a light-transmitting part 25b, and the light-transmitting part 25b has a partially thick part 25c. The partially thick part 25 is formed, for instance, so that a center P2 of a lower outer periphery set above a center P1 of a lower inner periphery, and at the same time, a diameter R2 of the lower outer periphery is set larger than that R1 of the lower inner periphery.