Fastener element and slide fastener

A fastener element to be attached to a fastener tape, the fastener element being made of metal, the fastener element comprising:

• an engagement portion;
• and
• a first extension and a second extension, the first extension and the second extension extending from the engagement portion, the first extension being disposed opposing the second extension, wherein
• each of the first extension and the second extension includes:
• a holding portion configured to hold a side edge of the fastener tape, the side edge of the fastener tape being held between the holding portion of the first extension and the holding portion of the second extension;
• and a thin portion disposed closer to the engagement portion than the holding portion in an extending direction of the first extension or the second extension,
• each of the first extension and the second extension has a thickness in a direction orthogonal to the corresponding extending direction and a longitudinal direction of the fastener tape, and
• in each of the first extension and the second extension, a minimum dimension of the thickness of the thin portion is smaller than a maximum dimension of the thickness of the holding portion.