A ball-catching piece comprises a main body of the above-mentioned ball-catching piece, a thumb-supporting piece provided in a thumb stall in the above-mentioned main body of the above-mentioned ball-catching piece to allow the position of a thumb to be fixed and to allow a fixed position of the above-mentioned thumb to be free, and a band provided in the above-mentioned main body of the above-mentioned ball-catching piece to allow a push to be exerted on a hand and to allow the push to be eliminated in the hand-width direction along which the backside of the above-mentioned hand is received and supported. The above-mentioned thumb-supporting piece comprises a first strap with which the above-mentioned thumb can be pushed from the side of the first finger and a second strap with which the above-mentioned thumb can be pushed from a side opposing the side of the above-mentioned first finger; the above-mentioned second strap is inserted through a first through-hole formed in outer leather of the above-mentioned main body of the above-mentioned ball-catching piece and is then inserted through a second through-hole formed in the above-mentioned band; and the second strap is used to enable the above-mentioned band to push the above-mentioned hand.