To provide an LED bulb that does not include any special heat dissipation means, is easy to handle and large in degree of freedom of design as a product, can be replaced with an existent incandescent lamp bulb freely, and induces no noise to peripheral electronic equipment.

The LED bulb which includes a plurality of LEDs and can be replaced with the existent incandescent lamp bulb includes a circuit which uses a voltage generated by directly rectifying constant-voltage commercial electric power, and a constant-current control circuit, wherein M=(-k+N√2(100-R)/100)(1-EL/100)I/QLED and QLED=I(1-EL/100)Ls≤46 are satisfied, where M is the number of at least one or more series-connected LEDs in each column.