To provide a power generation unit which utilizes a rotational force of driving wheels of a self-traveling vehicle and whose power generation capacity can be easily enlarged while ensuring safety.

A power generation unit (1) comprises a base (2), a substantially columnar rotary roller (5), a power generation mechanism (10) and a rotational force transfer mechanism (6). The rotary roller (5) is supported to the base (2) in a freely rotatable state by a rotary shaft extending in a horizontal direction and driven by driving wheels (51) in the state where the driving wheels (51) of a self-traveling vehicle (50) ride thereon. The power generation mechanism (10) is positioned higher than the rotary shaft of the rotary roller (5) and generates power by rotating a rotor (12) with respect to a stator (11). The rotational force transfer mechanism (6) transfers a rotational force of the rotary roller (5) to the rotor (12) of the power generation mechanism (10). A rotary shaft of the rotor of the power generation mechanism extends in a direction different from the rotary shaft of the rotary roller.