To provide a classification device or the like properly classifying a vector into one of a plurality of classes.

In this classification device 101, a minimization part 103 obtains a parameter matrix W by a steepest descent method or a conjugate gradient method so that an evaluation function J(W)=Remp+L(W) of a linear sum of a sampling error Remp when performing the classification by use of the array W and complicacy L(W) represented by an array norm of the array W is minimized in reference to a sample vector x[i] received by a sample reception part 102 and its class y[i], an identification value calculation part 105 decides an identification value fi(z) to an i-th class of a classification target vector z received by a target reception part 104 by an inner product between a column vector W[i] of an i-th column of the array W and z, and a classification part 106 classifies a classification target vector z into a class k from a maximum identification value fk(z).