A female connector comprising a body, the body comprising: a main body, the main body including: a connection hole for removably receiving a male connector (C2, C2') and a slot extending in a receiving direction of the male connector (C2, C2') and communicating with the connection hole; a base located on a removing direction side (Y') of the male connector (C2, C2') relative to the slot of the main body, the removing direction (Y') being opposite to the receiving direction; and a lock arm, the lock arm including: a first arm extending in the receiving direction from the base inside the slot such as to be adjacent to the connection hole and including a first free end (131b2), a middle portion extending from the first free end (131b2) of the first arm in a direction away from the connection hole, a second arm extending from the middle portion in the removing direction (Y') and being spaced from the first arm, and a lock projection extending from the first free end (131b2) of the first arm toward and into the connection hole, the lock projection being configured to fit in a lock hole of the male connector or abut a protrusion (C23') of the male connector (C2') from the removing direction side (Y'), wherein at least the first arm, the middle portion, and the second arm are configured to be compressed by and between the base and an edge on the receiving direction side of the lock hole of the male connector, or by and between the base and the protrusion (C23') of the male connector (C2'), when the lock projection is subjected to load in the removing direction (Y') from the edge or the protrusion (C23') of the male connector (C2, C2'). a main body, the main body including: a connection hole for removably receiving a male connector (C2, C2') and a slot extending in a receiving direction of the male connector (C2, C2') and communicating with the connection hole; a base located on a removing direction side (Y') of the male connector (C2, C2') relative to the slot of the main body, the removing direction (Y') being opposite to the receiving direction; and a lock arm, the lock arm including: a first arm extending in the receiving direction from the base inside the slot such as to be adjacent to the connection hole and including a first free end (131b2), a middle portion extending from the first free end (131b2) of the first arm in a direction away from the connection hole, a second arm extending from the middle portion in the removing direction (Y') and being spaced from the first arm, and a lock projection extending from the first free end (131b2) of the first arm toward and into the connection hole, the lock projection being configured to fit in a lock hole of the male connector or abut a protrusion (C23') of the male connector (C2') from the removing direction side (Y'), a first arm extending in the receiving direction from the base inside the slot such as to be adjacent to the connection hole and including a first free end (131b2), a middle portion extending from the first free end (131b2) of the first arm in a direction away from the connection hole, a second arm extending from the middle portion in the removing direction (Y') and being spaced from the first arm, and a lock projection extending from the first free end (131b2) of the first arm toward and into the connection hole, the lock projection being configured to fit in a lock hole of the male connector or abut a protrusion (C23') of the male connector (C2') from the removing direction side (Y'), wherein at least the first arm, the middle portion, and the second arm are configured to be compressed by and between the base and an edge on the receiving direction side of the lock hole of the male connector, or by and between the base and the protrusion (C23') of the male connector (C2'), when the lock projection is subjected to load in the removing direction (Y') from the edge or the protrusion (C23') of the male connector (C2, C2').