Golf club head and golf club

An iron golf club head comprising:

• a face having a ball striking surface and a back surface opposite to the ball striking surface,
• a sole portion constituting a bottom portion of the iron golf club head,
• an edge portion provided at the back surface and defining a cavity, the edge portion having an undercut portion,
• the back surface of the face having a thick portion located at a generally center portion thereof in a direction from a toe of the golf club head toward a heel of the golf club head, a thin portion located around the thick portion, and a tapered portion located between the thick portion and the thin portion,
• the thick portion having a first width which is a width in a direction from the heel of the golf club head toward the toe of the golf club head, and a second width which is a width in a direction from the sole of the golf club head toward a top of the golf club head and larger than the first width, the thick portion also having a first thickness,
• wherein the thick portion extends from an upper surface the sole portion located in the undercut portion,
• wherein the thick portion is connected to the sole portion via a fillet portion,
• the thin portion having a second thickness smaller than the first thickness, wherein the second thickness of the thin portion is a constant thickness,
• the tapered portion having a thickness reduced from a side of the thick portion toward a side of the thin portion, and
• at least a part of the thick portion being located in the undercut portion.