A crown gear deceleration mechanism comprising: a stator comprising a crown gear; a rotor comprising another crown gear that is located so as to be inclined to the crown gear; and an output shaft coupled to the rotor, wherein the stator comprises a stator tooth row in which N 1S stator teeth are circularly arranged, wherein the rotor comprises: a first rotor tooth row in which N 1 first rotor teeth are circularly arranged; and a second rotor tooth row in which N 2 second rotor teeth are circularly arranged, and wherein the output shaft comprises an output tooth row in which N 2S output teeth are circularly arranged, characterized in that: the rotor is configured to perform a precession while engaging the first rotor tooth row with the stator tooth row at places existing at both sides between which a devotion central line of the rotor intervenes, the rotor being configured to transmit rotation to the output shaft while engaging the second rotor tooth row with the output tooth row at places existing at both sides between which the devotion central line intervenes, and wherein the devotion central line is a line segment extending from a point at which the rotor is pressed to the stator most deeply to a point at which the rotor rises so as to be farthest from the stator. a stator comprising a crown gear; a rotor comprising another crown gear that is located so as to be inclined to the crown gear; and an output shaft coupled to the rotor, wherein the stator comprises a stator tooth row in which N 1S stator teeth are circularly arranged, wherein the rotor comprises: a first rotor tooth row in which N 1 first rotor teeth are circularly arranged; and a second rotor tooth row in which N 2 second rotor teeth are circularly arranged, and wherein the output shaft comprises an output tooth row in which N 2S output teeth are circularly arranged, characterized in that: the rotor is configured to perform a precession while engaging the first rotor tooth row with the stator tooth row at places existing at both sides between which a devotion central line of the rotor intervenes, the rotor being configured to transmit rotation to the output shaft while engaging the second rotor tooth row with the output tooth row at places existing at both sides between which the devotion central line intervenes, and wherein the devotion central line is a line segment extending from a point at which the rotor is pressed to the stator most deeply to a point at which the rotor rises so as to be farthest from the stator. a first rotor tooth row in which N 1 first rotor teeth are circularly arranged; and a second rotor tooth row in which N 2 second rotor teeth are circularly arranged, and wherein the output shaft comprises an output tooth row in which N 2S output teeth are circularly arranged, characterized in that: the rotor is configured to perform a precession while engaging the first rotor tooth row with the stator tooth row at places existing at both sides between which a devotion central line of the rotor intervenes, the rotor being configured to transmit rotation to the output shaft while engaging the second rotor tooth row with the output tooth row at places existing at both sides between which the devotion central line intervenes, and wherein the devotion central line is a line segment extending from a point at which the rotor is pressed to the stator most deeply to a point at which the rotor rises so as to be farthest from the stator. the rotor is configured to perform a precession while engaging the first rotor tooth row with the stator tooth row at places existing at both sides between which a devotion central line of the rotor intervenes, the rotor being configured to transmit rotation to the output shaft while engaging the second rotor tooth row with the output tooth row at places existing at both sides between which the devotion central line intervenes, and wherein the devotion central line is a line segment extending from a point at which the rotor is pressed to the stator most deeply to a point at which the rotor rises so as to be farthest from the stator.