A memory system includes a non-volatile memory including first and second memory chips connected to a channel, each chip outputting a first signal indicating whether the chip is in a busy state, a first queue storing commands to be executed by the first chip, a second queue storing commands to be executed by the second chip, a processor configured to issue a second signal indicating whether a command in the first or second queue is a first-type or a second-type command, the first-type command causing the first or second chip to be in the busy state longer than the second-type command, a first arbiter selecting from the first and second queues a command to be executed next based on the first and second signals, and an interface controller sending the selected command via the channel to the first or second memory chip.