A decoder comprising a processor and a memory, wherein the processor, using the memory, inverse quantizes data corresponding to a current block of an image performs an inverse secondary transform, using one candidate of the inverse secondary transform selected from candidates of the inverse secondary transform, on a result of the inverse quantization to generate second transform coefficients, the candidates of the inverse secondary transform including transform bases for the inverse secondary transform and a skip of the inverse secondary transform and performs an inverse primary transform, using one candidate of the inverse primary transform selected from candidates of the inverse primary transform, on the second transform coefficients or the result of the inverse quantization to generate first transform coefficients, the candidates of the inverse primary transform including transform bases for the inverse primary transform.