- Bats Right, Throws Right
- Height 5' 10", Weight 150 lb.
- High School Yura Ikuei High School
Kobayashi was a sixth-round draft pick in 1971. He debuted with the Yomiuri Giants in 1973, allowing 5 hits and no runs in 11 1/3 IP. He went 8-5 with two saves and a 2.42 ERA in 1974, with 29 walks in 130 1/3 IP. Had he qualified, he would have been 8th in the Central League in ERA. For the Giants in 1975, the thin right-hander was 5-6 with a 3.31 ERA; he only fanned 42 in 106 1/3 innings and hit 14 batters, most in the CL.
Kobayashi had a 18-8, 2.99 record with two saves in 1976 and made his first All-Star squad. He was second in the league in ERA, only .001 behind Takamasa Suzuki. He was two wins behind leader Kojiro Ikegaya. He lost game one of the 1976 Japan Series but won games four and six; Yomiuri went on to lose in seven to the Hankyu Braves. Kobayashi was 2-1 with a save and a 2.79 ERA in the Series and went 3 for 7 at the plate as well.
Kobayashi was 18-8 again in 1977 and also saved 7 games. His strikeout rate rising, he fanned 155 in 216 1/3 innings. His ERA was 2.92. Once again an All-Star, he tied Senichi Hoshino, Kenji Furusawa and Takenori Emoto for the league in shutouts (3). He made the Best Nine and won the Sawamura Award. He was two wins behind leader Satoshi Takahashi and was second to Hisao Niura in ERA. He struggled in the postseason, going 0-1 with a 5.88 ERA in the 1977 Japan Series with a game one loss.
Kobayashi then went to the Hanshin Tigers as part of the Suguru Egawa affair. He had a great comeback in 1979, going 22-9 with a save and a 2.89 ERA. He fanned 200 and allowed 227 hits in 273 2/3 IP. He was an All-Star and led the league in innings, wins, complete games (17), batters faced (1,129), hits allowed, shutouts (5) and runs allowed (101). He was 5th in ERA. He was again a Best Nine pick and Sawamura Award winner.
The Tottori native fell to 15-14, 3.02 in 1980 and led once more in innings (280 1/3), complete games (21), hit batsmen (20) and batters faced (1,127). The 20 hit batsmen were a league record. He also surrendered 36 home runs, most in the CL. He was an All-Star for the fifth straight time. He was 9th in the league in ERA.
An All-Star yet again in 1981, the veteran was 16-10 with two saves and a 3.01 ERA. He led the league with 14 hit batsmen. On April 28, he got his 100th career victory. On August 4, he became the 62nd player in NPB history to strike out 1,000 batters. He was 4th in the league in ERA.
Kobayashi was 11-9 with a 3.42 ERA in 1982. He had a 13-14, 4.05 record with a save in 1983 and made his 7th All-Star team but led the league in losses (tied with three others) and runs allowed (96). He then retired.
Kobayashi went 139-95 with 17 saves and a 3.18 ERA in 374 games. In 2,029 1/3 innings, he allowed 1,824 hits.
Kobayashi became a TV baseball commentator and then coached for the Kintetsu Buffaloes.
Through 2008, he is 12th in NPB history in hit batsmen (111).