Electric resistance welded steel pipe and method for manufacturing the same

An electric resistance welded steel pipe comprising a base metal zone and a weld, wherein

• steel microstructures at a wall-thickness-wise middle of the base metal zone are steel microstructures in which a bcc phase is present in a volume fraction greater than or equal to 80%, an average grain size is less than or equal to 15.0 μm, and an A value, defined by equation (1), is 0.55 or greater and 0.85 or less;
• a yield ratio in a pipe axis direction is less than or equal to 90%;
• and
• a Charpy absorbed energy at −40° C. of the base metal zone is greater than or equal to 100 J,
• A=φ/((πρ/2)1/2×b) (1)
• where φ is a parameter representing a working ratio determined by X-ray diffraction, ρ is a dislocation density (m−2), b is a Burgers vector (m) of dislocations, and π is a ratio of a circumference of a circle to a diameter of the circle.